diff --git a/app/src/components/settings/panels/MascotPanel.tsx b/app/src/components/settings/panels/MascotPanel.tsx
index c9e105f0c..2c72de375 100644
--- a/app/src/components/settings/panels/MascotPanel.tsx
+++ b/app/src/components/settings/panels/MascotPanel.tsx
@@ -1,5 +1,6 @@
 import { useEffect, useRef, useState } from 'react';
 
+import { CustomGifMascot } from '../../../features/human/Mascot';
 import { BackendMascot } from '../../../features/human/Mascot/backend/BackendMascot';
 import type { MascotDetail, MascotSummary } from '../../../features/human/Mascot/backend/types';
 import { getMascotPalette, type MascotColor } from '../../../features/human/Mascot/mascotPalette';
@@ -9,13 +10,16 @@ import { fetchMascotList, getCachedMascotDetail } from '../../../services/mascot
 import { useAppDispatch, useAppSelector } from '../../../store/hooks';
 import {
   DEFAULT_MASCOT_COLOR,
+  isCustomMascotGifUrl,
   type MascotVoiceGender,
+  selectCustomMascotGifUrl,
   selectEffectiveMascotVoiceId,
   selectMascotColor,
   selectMascotVoiceGender,
   selectMascotVoiceId,
   selectMascotVoiceUseLocaleDefault,
   selectSelectedMascotId,
+  setCustomMascotGifUrl,
   setMascotColor,
   setMascotVoiceGender,
   setMascotVoiceId,
@@ -52,6 +56,7 @@ const MascotPanel = () => {
   const dispatch = useAppDispatch();
   const storedColor = useAppSelector(selectMascotColor);
   const selectedMascotId = useAppSelector(selectSelectedMascotId);
+  const customMascotGifUrl = useAppSelector(selectCustomMascotGifUrl);
   const storedVoiceId = useAppSelector(selectMascotVoiceId);
   const voiceGender = useAppSelector(selectMascotVoiceGender);
   const useLocaleDefault = useAppSelector(selectMascotVoiceUseLocaleDefault);
@@ -64,6 +69,8 @@ const MascotPanel = () => {
   const [backendListError, setBackendListError] = useState<string | null>(null);
   const [activeDetail, setActiveDetail] = useState<MascotDetail | null>(null);
   const [detailError, setDetailError] = useState<string | null>(null);
+  const [customGifDraft, setCustomGifDraft] = useState<string>(customMascotGifUrl ?? '');
+  const [customGifError, setCustomGifError] = useState<string | null>(null);
 
   // Voice picker state — paste-mode is sticky because we can't derive it
   // from the stored value alone (a curated preset id and "user is
@@ -138,6 +145,35 @@ const MascotPanel = () => {
 
   const handleSelectBackend = (id: string | null) => {
     dispatch(setSelectedMascotId(id));
+    setCustomGifError(null);
+    if (id == null) {
+      setCustomGifDraft('');
+      dispatch(setCustomMascotGifUrl(null));
+    } else {
+      setCustomGifDraft('');
+    }
+  };
+
+  const onSaveCustomGif = () => {
+    const trimmed = customGifDraft.trim();
+    setCustomGifDraft(trimmed);
+    if (trimmed.length === 0) {
+      setCustomGifError(null);
+      dispatch(setCustomMascotGifUrl(null));
+      return;
+    }
+    if (!isCustomMascotGifUrl(trimmed)) {
+      setCustomGifError(t('settings.mascot.customGifError'));
+      return;
+    }
+    setCustomGifError(null);
+    dispatch(setCustomMascotGifUrl(trimmed));
+  };
+
+  const onResetCustomGif = () => {
+    setCustomGifDraft('');
+    setCustomGifError(null);
+    dispatch(setCustomMascotGifUrl(null));
   };
 
   // Filter the menu to colors the asset pipeline currently supports — guards
@@ -455,6 +491,56 @@ const MascotPanel = () => {
           <h3 className="text-xs font-semibold uppercase tracking-wider text-stone-400 dark:text-neutral-500 mb-2 px-1">
             {t('settings.mascot.characterHeading')}
           </h3>
+          <div className="mb-3 bg-white dark:bg-neutral-900 rounded-xl border border-stone-200 dark:border-neutral-800 p-4 space-y-3">
+            <label className="block space-y-1">
+              <span className="text-xs font-medium text-stone-600 dark:text-neutral-300">
+                {t('settings.mascot.customGifHeading')}
+              </span>
+              <div className="flex gap-2">
+                <input
+                  aria-label={t('settings.mascot.customGifLabel')}
+                  data-testid="mascot-custom-gif-input"
+                  value={customGifDraft}
+                  placeholder="https://example.com/avatar.gif"
+                  onChange={e => {
+                    setCustomGifDraft(e.target.value);
+                    setCustomGifError(null);
+                  }}
+                  className="flex-1 rounded-md border border-stone-200 dark:border-neutral-800 bg-white dark:bg-neutral-900 px-3 py-2 text-sm text-stone-900 dark:text-neutral-100 placeholder:text-stone-400 dark:placeholder:text-neutral-500 focus:outline-none focus:ring-1 focus:ring-primary-400"
+                />
+                <button
+                  type="button"
+                  data-testid="mascot-custom-gif-save"
+                  onClick={onSaveCustomGif}
+                  disabled={customGifDraft.trim() === (customMascotGifUrl ?? '').trim()}
+                  className="px-3 py-1.5 text-xs rounded-md bg-primary-600 hover:bg-primary-700 disabled:opacity-60 text-white">
+                  {t('common.save')}
+                </button>
+                <button
+                  type="button"
+                  data-testid="mascot-custom-gif-reset"
+                  onClick={onResetCustomGif}
+                  disabled={customMascotGifUrl == null && customGifDraft.trim().length === 0}
+                  className="px-3 py-1.5 text-xs rounded-md border border-stone-300 dark:border-neutral-700 hover:border-stone-400 dark:hover:border-neutral-600 disabled:opacity-60 text-stone-700 dark:text-neutral-200">
+                  {t('common.reset')}
+                </button>
+              </div>
+            </label>
+            {customGifError && (
+              <p
+                data-testid="mascot-custom-gif-error"
+                className="text-xs text-coral-700 dark:text-coral-300">
+                {customGifError}
+              </p>
+            )}
+            {customMascotGifUrl && (
+              <div className="flex justify-center rounded-lg border border-stone-100 dark:border-neutral-800 bg-stone-50 dark:bg-neutral-800/60 p-3">
+                <div style={{ width: 128, height: 128 }}>
+                  <CustomGifMascot src={customMascotGifUrl} />
+                </div>
+              </div>
+            )}
+          </div>
           <div className="bg-white dark:bg-neutral-900 rounded-xl border border-stone-200 dark:border-neutral-800 overflow-hidden">
             {backendListError && (
               <p className="p-4 text-sm text-coral-700 dark:text-coral-300">
@@ -477,14 +563,14 @@ const MascotPanel = () => {
                   <button
                     type="button"
                     onClick={() => handleSelectBackend(null)}
-                    aria-pressed={selectedMascotId == null}
+                    aria-pressed={selectedMascotId == null && customMascotGifUrl == null}
                     className={`flex w-full items-center justify-between px-4 py-3 text-left text-sm hover:bg-stone-50 dark:hover:bg-neutral-800/60 dark:bg-neutral-800/60 dark:hover:bg-neutral-800/60 ${
-                      selectedMascotId == null
+                      selectedMascotId == null && customMascotGifUrl == null
                         ? 'bg-stone-50 dark:bg-neutral-800/60 font-medium'
                         : ''
                     }`}>
                     <span>{t('settings.mascot.localDefault')}</span>
-                    {selectedMascotId == null && (
+                    {selectedMascotId == null && customMascotGifUrl == null && (
                       <span className="text-[10px] uppercase text-primary-600 dark:text-primary-300">
                         {t('settings.mascot.active')}
                       </span>
diff --git a/app/src/components/settings/panels/__tests__/MascotPanel.test.tsx b/app/src/components/settings/panels/__tests__/MascotPanel.test.tsx
index d5b290177..6f126aab7 100644
--- a/app/src/components/settings/panels/__tests__/MascotPanel.test.tsx
+++ b/app/src/components/settings/panels/__tests__/MascotPanel.test.tsx
@@ -7,6 +7,7 @@ import { beforeEach, describe, expect, it, vi } from 'vitest';
 
 import mascotReducer, {
   DEFAULT_MASCOT_COLOR,
+  setCustomMascotGifUrl,
   setMascotColor,
   setSelectedMascotId,
 } from '../../../../store/mascotSlice';
@@ -222,5 +223,41 @@ describe('MascotPanel — mascotSlice rehydrate guard', () => {
       fireEvent.click(localRow);
       expect(store.getState().mascot.selectedMascotId).toBeNull();
     });
+
+    it('saves a custom GIF avatar and previews it', () => {
+      const { store } = renderPanel();
+      fireEvent.change(screen.getByTestId('mascot-custom-gif-input'), {
+        target: { value: '  https://example.com/avatar.gif  ' },
+      });
+      fireEvent.click(screen.getByTestId('mascot-custom-gif-save'));
+
+      expect(store.getState().mascot.customMascotGifUrl).toBe('https://example.com/avatar.gif');
+      expect(screen.getByTestId('custom-gif-mascot')).toHaveAttribute(
+        'src',
+        'https://example.com/avatar.gif'
+      );
+    });
+
+    it('rejects non-GIF avatar sources in the panel', () => {
+      const { store } = renderPanel();
+      fireEvent.change(screen.getByTestId('mascot-custom-gif-input'), {
+        target: { value: 'https://example.com/avatar.svg' },
+      });
+      fireEvent.click(screen.getByTestId('mascot-custom-gif-save'));
+
+      expect(store.getState().mascot.customMascotGifUrl).toBeNull();
+      expect(screen.getByTestId('mascot-custom-gif-error')).toHaveTextContent('HTTPS .gif');
+    });
+
+    it('selecting a backend mascot clears the custom GIF avatar', async () => {
+      const store = buildStore();
+      store.dispatch(setCustomMascotGifUrl('https://example.com/avatar.gif'));
+      fetchMascotListMock.mockResolvedValueOnce([summary]);
+      renderPanel(store);
+      fireEvent.click(await screen.findByTestId('backend-mascot-yellow'));
+
+      expect(store.getState().mascot.selectedMascotId).toBe('yellow');
+      expect(store.getState().mascot.customMascotGifUrl).toBeNull();
+    });
   });
 });
diff --git a/app/src/features/human/HumanPage.test.tsx b/app/src/features/human/HumanPage.test.tsx
index 50ecd2014..7c7736ddf 100644
--- a/app/src/features/human/HumanPage.test.tsx
+++ b/app/src/features/human/HumanPage.test.tsx
@@ -12,7 +12,7 @@ import { Provider } from 'react-redux';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
 import chatRuntimeReducer, { setToolTimelineForThread } from '../../store/chatRuntimeSlice';
-import mascotReducer from '../../store/mascotSlice';
+import mascotReducer, { setCustomMascotGifUrl } from '../../store/mascotSlice';
 import threadReducer, { setSelectedThread } from '../../store/threadSlice';
 // ── Static import (after mocks are hoisted) ──────────────────────────────
 import HumanPage from './HumanPage';
@@ -25,6 +25,9 @@ vi.mock('../../pages/Conversations', () => ({
 
 vi.mock('./Mascot', () => ({
   YellowMascot: () => <div data-testid="mascot-stub" />,
+  CustomGifMascot: ({ src, face }: { src: string; face?: string }) => (
+    <img data-testid="custom-gif-mascot" data-face={face} src={src} alt="" />
+  ),
   Ghosty: ({ face, bodyColor }: { face?: string; bodyColor?: string }) => (
     <div data-testid="ghosty-submascot" data-face={face} data-body-color={bodyColor} />
   ),
@@ -136,4 +139,17 @@ describe('HumanPage — speak-replies localStorage persistence', () => {
     expect(screen.getByText('Researcher')).toBeInTheDocument();
     expect(screen.getByText('Iteration 1/3')).toBeInTheDocument();
   });
+
+  it('renders a custom GIF mascot when one is configured', () => {
+    const store = buildMinimalStore();
+    store.dispatch(setCustomMascotGifUrl('https://example.com/avatar.gif'));
+
+    renderHumanPage(store);
+
+    expect(screen.getByTestId('custom-gif-mascot')).toHaveAttribute(
+      'src',
+      'https://example.com/avatar.gif'
+    );
+    expect(screen.queryByTestId('mascot-stub')).not.toBeInTheDocument();
+  });
 });
diff --git a/app/src/features/human/HumanPage.tsx b/app/src/features/human/HumanPage.tsx
index 8def76542..65c8036bc 100644
--- a/app/src/features/human/HumanPage.tsx
+++ b/app/src/features/human/HumanPage.tsx
@@ -4,8 +4,8 @@ import { useT } from '../../lib/i18n/I18nContext';
 import Conversations from '../../pages/Conversations';
 import type { ToolTimelineEntry } from '../../store/chatRuntimeSlice';
 import { useAppSelector } from '../../store/hooks';
-import { selectMascotColor } from '../../store/mascotSlice';
-import { YellowMascot } from './Mascot';
+import { selectCustomMascotGifUrl, selectMascotColor } from '../../store/mascotSlice';
+import { CustomGifMascot, YellowMascot } from './Mascot';
 import { SubMascotLayer } from './SubMascotLayer';
 import { useHumanMascot } from './useHumanMascot';
 
@@ -29,6 +29,7 @@ const HumanPage = () => {
   // Visemes are intentionally unused — the YellowMascot has its own talking lipsync.
   const { face } = useHumanMascot({ speakReplies });
   const mascotColor = useAppSelector(selectMascotColor);
+  const customMascotGifUrl = useAppSelector(selectCustomMascotGifUrl);
   const subMascotTimeline = useAppSelector(state => {
     const threadId = state.thread.selectedThreadId ?? state.thread.activeThreadId;
     return threadId
@@ -50,7 +51,11 @@ const HumanPage = () => {
       {/* Mascot stage — fills the area to the left of the reserved sidebar column. */}
       <div className="absolute inset-y-0 left-0 right-[436px] flex items-center justify-center">
         <div className="relative w-[min(80vh,90%)] aspect-square">
-          <YellowMascot face={face} mascotColor={mascotColor} />
+          {customMascotGifUrl ? (
+            <CustomGifMascot src={customMascotGifUrl} face={face} />
+          ) : (
+            <YellowMascot face={face} mascotColor={mascotColor} />
+          )}
           <SubMascotLayer entries={subMascotTimeline} />
         </div>
       </div>
diff --git a/app/src/features/human/Mascot/CustomGifMascot.test.tsx b/app/src/features/human/Mascot/CustomGifMascot.test.tsx
new file mode 100644
index 000000000..e50bc8f25
--- /dev/null
+++ b/app/src/features/human/Mascot/CustomGifMascot.test.tsx
@@ -0,0 +1,16 @@
+import { render, screen } from '@testing-library/react';
+import { describe, expect, it } from 'vitest';
+
+import { CustomGifMascot } from './CustomGifMascot';
+
+describe('CustomGifMascot', () => {
+  it('renders a no-referrer animated avatar image', () => {
+    render(<CustomGifMascot src="https://example.com/avatar.gif" face="speaking" />);
+
+    const mascot = screen.getByTestId('custom-gif-mascot') as HTMLImageElement;
+    expect(mascot).toHaveAttribute('src', 'https://example.com/avatar.gif');
+    expect(mascot).toHaveAttribute('data-face', 'speaking');
+    expect(mascot).toHaveAttribute('referrerpolicy', 'no-referrer');
+    expect(mascot).toHaveAttribute('aria-hidden', 'true');
+  });
+});
diff --git a/app/src/features/human/Mascot/CustomGifMascot.tsx b/app/src/features/human/Mascot/CustomGifMascot.tsx
new file mode 100644
index 000000000..48847d84e
--- /dev/null
+++ b/app/src/features/human/Mascot/CustomGifMascot.tsx
@@ -0,0 +1,21 @@
+import type { MascotFace } from './Ghosty';
+
+export interface CustomGifMascotProps {
+  src: string;
+  face?: MascotFace;
+}
+
+export function CustomGifMascot({ src, face = 'idle' }: CustomGifMascotProps) {
+  return (
+    <img
+      src={src}
+      alt=""
+      aria-hidden="true"
+      data-testid="custom-gif-mascot"
+      data-face={face}
+      referrerPolicy="no-referrer"
+      draggable={false}
+      className="block h-full w-full select-none object-contain"
+    />
+  );
+}
diff --git a/app/src/features/human/Mascot/index.ts b/app/src/features/human/Mascot/index.ts
index fb7e400c2..1d3816fde 100644
--- a/app/src/features/human/Mascot/index.ts
+++ b/app/src/features/human/Mascot/index.ts
@@ -1,5 +1,7 @@
 export { Ghosty } from './Ghosty';
 export type { GhostyProps, MascotFace } from './Ghosty';
+export { CustomGifMascot } from './CustomGifMascot';
+export type { CustomGifMascotProps } from './CustomGifMascot';
 export { YellowMascot } from './YellowMascot';
 export type { YellowMascotProps } from './YellowMascot';
 export { lerpViseme, VISEMES, visemePath } from './visemes';
diff --git a/app/src/lib/i18n/chunks/ar-5.ts b/app/src/lib/i18n/chunks/ar-5.ts
index 448310af1..b3637ed29 100644
--- a/app/src/lib/i18n/chunks/ar-5.ts
+++ b/app/src/lib/i18n/chunks/ar-5.ts
@@ -200,6 +200,11 @@ const ar5: TranslationMap = {
   'settings.mascot.active': 'نشط',
   'settings.mascot.characterDesc': 'وصف الشخصية',
   'settings.mascot.characterHeading': 'عنوان الشخصية',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'وصف اللون',
   'settings.mascot.colorHeading': 'عنوان اللون',
   'settings.mascot.loadingLibrary': 'جارٍ تحميل مكتبة OpenHuman…',
diff --git a/app/src/lib/i18n/chunks/bn-5.ts b/app/src/lib/i18n/chunks/bn-5.ts
index e24e5c08a..77b237808 100644
--- a/app/src/lib/i18n/chunks/bn-5.ts
+++ b/app/src/lib/i18n/chunks/bn-5.ts
@@ -206,6 +206,11 @@ const bn5: TranslationMap = {
   'settings.mascot.active': 'সক্রিয়',
   'settings.mascot.characterDesc': 'চরিত্রের বিবরণ',
   'settings.mascot.characterHeading': 'চরিত্রের শিরোনাম',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'রঙের বিবরণ',
   'settings.mascot.colorHeading': 'রঙের শিরোনাম',
   'settings.mascot.loadingLibrary': 'OpenHuman লাইব্রেরি লোড হচ্ছে…',
diff --git a/app/src/lib/i18n/chunks/en-5.ts b/app/src/lib/i18n/chunks/en-5.ts
index 6c170c15d..ae4288bb5 100644
--- a/app/src/lib/i18n/chunks/en-5.ts
+++ b/app/src/lib/i18n/chunks/en-5.ts
@@ -204,6 +204,10 @@ const en5: TranslationMap = {
   'settings.mascot.active': 'Active',
   'settings.mascot.characterDesc': 'Character desc',
   'settings.mascot.characterHeading': 'Character heading',
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'Color desc',
   'settings.mascot.colorHeading': 'Color heading',
   'settings.mascot.loadingLibrary': 'Loading OpenHuman library…',
diff --git a/app/src/lib/i18n/chunks/es-5.ts b/app/src/lib/i18n/chunks/es-5.ts
index 892486103..eeea2351b 100644
--- a/app/src/lib/i18n/chunks/es-5.ts
+++ b/app/src/lib/i18n/chunks/es-5.ts
@@ -210,6 +210,11 @@ const es5: TranslationMap = {
   'settings.mascot.active': 'Activo',
   'settings.mascot.characterDesc': 'Descripción del personaje',
   'settings.mascot.characterHeading': 'Encabezado del personaje',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'Descripción del color',
   'settings.mascot.colorHeading': 'Encabezado del color',
   'settings.mascot.loadingLibrary': 'Cargando biblioteca de OpenHuman…',
diff --git a/app/src/lib/i18n/chunks/fr-5.ts b/app/src/lib/i18n/chunks/fr-5.ts
index 7a7208b6e..4b90263bb 100644
--- a/app/src/lib/i18n/chunks/fr-5.ts
+++ b/app/src/lib/i18n/chunks/fr-5.ts
@@ -212,6 +212,11 @@ const fr5: TranslationMap = {
   'settings.mascot.active': 'Actif',
   'settings.mascot.characterDesc': 'Description du personnage',
   'settings.mascot.characterHeading': 'Titre du personnage',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'Description de la couleur',
   'settings.mascot.colorHeading': 'Titre de la couleur',
   'settings.mascot.loadingLibrary': 'Chargement de la bibliothèque OpenHuman…',
diff --git a/app/src/lib/i18n/chunks/hi-5.ts b/app/src/lib/i18n/chunks/hi-5.ts
index deb7ef915..aeb928cee 100644
--- a/app/src/lib/i18n/chunks/hi-5.ts
+++ b/app/src/lib/i18n/chunks/hi-5.ts
@@ -206,6 +206,11 @@ const hi5: TranslationMap = {
   'settings.mascot.active': 'एक्टिव',
   'settings.mascot.characterDesc': 'कैरेक्टर विवरण',
   'settings.mascot.characterHeading': 'कैरेक्टर शीर्षक',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'रंग विवरण',
   'settings.mascot.colorHeading': 'रंग शीर्षक',
   'settings.mascot.loadingLibrary': 'OpenHuman लाइब्रेरी लोड हो रही है…',
diff --git a/app/src/lib/i18n/chunks/id-5.ts b/app/src/lib/i18n/chunks/id-5.ts
index e7d118def..a55b6b860 100644
--- a/app/src/lib/i18n/chunks/id-5.ts
+++ b/app/src/lib/i18n/chunks/id-5.ts
@@ -206,6 +206,11 @@ const id5: TranslationMap = {
   'settings.mascot.active': 'Aktif',
   'settings.mascot.characterDesc': 'Deskripsi karakter',
   'settings.mascot.characterHeading': 'Judul karakter',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'Deskripsi warna',
   'settings.mascot.colorHeading': 'Judul warna',
   'settings.mascot.loadingLibrary': 'Memuat perpustakaan OpenHuman...',
diff --git a/app/src/lib/i18n/chunks/it-5.ts b/app/src/lib/i18n/chunks/it-5.ts
index 93494cf58..d38c4934d 100644
--- a/app/src/lib/i18n/chunks/it-5.ts
+++ b/app/src/lib/i18n/chunks/it-5.ts
@@ -210,6 +210,11 @@ const it5: TranslationMap = {
   'settings.mascot.active': 'Attivo',
   'settings.mascot.characterDesc': 'Descrizione personaggio',
   'settings.mascot.characterHeading': 'Intestazione personaggio',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'Descrizione colore',
   'settings.mascot.colorHeading': 'Intestazione colore',
   'settings.mascot.loadingLibrary': 'Caricamento libreria OpenHuman…',
diff --git a/app/src/lib/i18n/chunks/ko-5.ts b/app/src/lib/i18n/chunks/ko-5.ts
index 85e1f7e2b..249688d2e 100644
--- a/app/src/lib/i18n/chunks/ko-5.ts
+++ b/app/src/lib/i18n/chunks/ko-5.ts
@@ -167,6 +167,10 @@ const ko5: TranslationMap = {
   'settings.mascot.active': '활성',
   'settings.mascot.characterDesc': '캐릭터 설명',
   'settings.mascot.characterHeading': '캐릭터 제목',
+  'settings.mascot.customGifError':
+    'HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL 또는 로컬 .gif 경로를 입력하세요.',
+  'settings.mascot.customGifHeading': '사용자 지정 GIF 아바타',
+  'settings.mascot.customGifLabel': '사용자 지정 GIF 아바타 URL',
   'settings.mascot.colorDesc': '색상 설명',
   'settings.mascot.colorHeading': '색상 제목',
   'settings.mascot.loadingLibrary': 'OpenHuman 라이브러리 불러오는 중…',
diff --git a/app/src/lib/i18n/chunks/pt-5.ts b/app/src/lib/i18n/chunks/pt-5.ts
index a0c045d5c..50dacf095 100644
--- a/app/src/lib/i18n/chunks/pt-5.ts
+++ b/app/src/lib/i18n/chunks/pt-5.ts
@@ -211,6 +211,11 @@ const pt5: TranslationMap = {
   'settings.mascot.active': 'Ativo',
   'settings.mascot.characterDesc': 'Descrição do personagem',
   'settings.mascot.characterHeading': 'Título do personagem',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'Descrição de cor',
   'settings.mascot.colorHeading': 'Título de cor',
   'settings.mascot.loadingLibrary': 'Carregando biblioteca do OpenHuman…',
diff --git a/app/src/lib/i18n/chunks/ru-5.ts b/app/src/lib/i18n/chunks/ru-5.ts
index fc302f03f..65cd65284 100644
--- a/app/src/lib/i18n/chunks/ru-5.ts
+++ b/app/src/lib/i18n/chunks/ru-5.ts
@@ -207,6 +207,11 @@ const ru5: TranslationMap = {
   'settings.mascot.active': 'Активно',
   'settings.mascot.characterDesc': 'Описание персонажа',
   'settings.mascot.characterHeading': 'Персонаж',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': 'Описание цвета',
   'settings.mascot.colorHeading': 'Цвет',
   'settings.mascot.loadingLibrary': 'Загрузка библиотеки OpenHuman…',
diff --git a/app/src/lib/i18n/chunks/zh-CN-5.ts b/app/src/lib/i18n/chunks/zh-CN-5.ts
index b40b6af93..36de298f4 100644
--- a/app/src/lib/i18n/chunks/zh-CN-5.ts
+++ b/app/src/lib/i18n/chunks/zh-CN-5.ts
@@ -190,6 +190,11 @@ const zhCN5: TranslationMap = {
   'settings.mascot.active': '活跃',
   'settings.mascot.characterDesc': '选择你的 OpenHuman 角色',
   'settings.mascot.characterHeading': '角色',
+  // TODO: translate custom GIF mascot strings.
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.colorDesc': '选择颜色方案',
   'settings.mascot.colorHeading': '颜色',
   'settings.mascot.loadingLibrary': '正在加载 OpenHuman 库…',
diff --git a/app/src/lib/i18n/en.ts b/app/src/lib/i18n/en.ts
index 078bae24a..22932e474 100644
--- a/app/src/lib/i18n/en.ts
+++ b/app/src/lib/i18n/en.ts
@@ -1999,6 +1999,10 @@ const en: TranslationMap = {
   'settings.mascot.active': 'Active',
   'settings.mascot.characterDesc': 'Choose your OpenHuman character.',
   'settings.mascot.characterHeading': 'Character',
+  'settings.mascot.customGifError':
+    'Enter an HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL, or local .gif path.',
+  'settings.mascot.customGifHeading': 'Custom GIF avatar',
+  'settings.mascot.customGifLabel': 'Custom GIF avatar URL',
   'settings.mascot.characterPreview': 'Preview',
   'settings.mascot.characterStates': 'states',
   'settings.mascot.characterVisemes': 'visemes',
diff --git a/app/src/lib/i18n/ko.ts b/app/src/lib/i18n/ko.ts
index 5e85ff7b8..3d21380ba 100644
--- a/app/src/lib/i18n/ko.ts
+++ b/app/src/lib/i18n/ko.ts
@@ -1842,6 +1842,10 @@ const ko: TranslationMap = {
   'settings.mascot.active': '활성',
   'settings.mascot.characterDesc': 'OpenHuman 캐릭터를 선택하세요.',
   'settings.mascot.characterHeading': '캐릭터',
+  'settings.mascot.customGifError':
+    'HTTPS .gif URL, loopback HTTP .gif URL, file:// .gif URL 또는 로컬 .gif 경로를 입력하세요.',
+  'settings.mascot.customGifHeading': '사용자 지정 GIF 아바타',
+  'settings.mascot.customGifLabel': '사용자 지정 GIF 아바타 URL',
   'settings.mascot.characterPreview': '미리보기',
   'settings.mascot.characterStates': '상태',
   'settings.mascot.characterVisemes': '입 모양',
diff --git a/app/src/store/__tests__/mascotSlice.test.ts b/app/src/store/__tests__/mascotSlice.test.ts
index 7c47a237d..23910c4c2 100644
--- a/app/src/store/__tests__/mascotSlice.test.ts
+++ b/app/src/store/__tests__/mascotSlice.test.ts
@@ -3,10 +3,14 @@ import { describe, expect, it } from 'vitest';
 
 import reducer, {
   DEFAULT_MASCOT_COLOR,
+  isCustomMascotGifUrl,
+  MAX_CUSTOM_MASCOT_GIF_URL_LEN,
   MAX_MASCOT_VOICE_ID_LEN,
+  selectCustomMascotGifUrl,
   selectMascotColor,
   selectMascotVoiceId,
   selectSelectedMascotId,
+  setCustomMascotGifUrl,
   setMascotColor,
   setMascotVoiceId,
   setSelectedMascotId,
@@ -199,4 +203,78 @@ describe('mascotSlice', () => {
       expect(state.selectedMascotId).toBeNull();
     });
   });
+
+  describe('custom mascot GIF avatar', () => {
+    it('defaults to null', () => {
+      const state = reducer(undefined, { type: '@@INIT' });
+      expect(state.customMascotGifUrl).toBeNull();
+      expect(selectCustomMascotGifUrl({ mascot: state })).toBeNull();
+    });
+
+    it('stores a trimmed HTTPS GIF URL', () => {
+      const state = reducer(
+        undefined,
+        setCustomMascotGifUrl('  https://example.com/avatar.gif?size=2  ')
+      );
+      expect(state.customMascotGifUrl).toBe('https://example.com/avatar.gif?size=2');
+    });
+
+    it('accepts local GIF paths and loopback HTTP URLs', () => {
+      expect(isCustomMascotGifUrl('/Users/me/avatar.gif')).toBe(true);
+      expect(isCustomMascotGifUrl('~/Pictures/avatar.gif')).toBe(true);
+      expect(isCustomMascotGifUrl('http://localhost/avatar.gif')).toBe(true);
+      expect(isCustomMascotGifUrl('http://127.0.0.1/avatar.gif')).toBe(true);
+    });
+
+    it('rejects unsafe or non-GIF avatar sources', () => {
+      expect(isCustomMascotGifUrl('javascript:alert(1)')).toBe(false);
+      expect(isCustomMascotGifUrl('http://example.com/avatar.gif')).toBe(false);
+      expect(isCustomMascotGifUrl('https://example.com/avatar.svg')).toBe(false);
+      expect(isCustomMascotGifUrl('https://example.com/avatar.png')).toBe(false);
+    });
+
+    it('rejects oversize avatar sources', () => {
+      const tooLong = `https://example.com/${'x'.repeat(MAX_CUSTOM_MASCOT_GIF_URL_LEN)}.gif`;
+      const state = reducer(undefined, setCustomMascotGifUrl(tooLong));
+      expect(state.customMascotGifUrl).toBeNull();
+    });
+
+    it('clears backend mascot id when a custom GIF is set', () => {
+      let state = reducer(undefined, setSelectedMascotId('yellow'));
+      state = reducer(state, setCustomMascotGifUrl('https://example.com/avatar.gif'));
+      expect(state.customMascotGifUrl).toBe('https://example.com/avatar.gif');
+      expect(state.selectedMascotId).toBeNull();
+    });
+
+    it('clears custom GIF when a backend mascot is selected', () => {
+      let state = reducer(undefined, setCustomMascotGifUrl('https://example.com/avatar.gif'));
+      state = reducer(state, setSelectedMascotId('yellow'));
+      expect(state.selectedMascotId).toBe('yellow');
+      expect(state.customMascotGifUrl).toBeNull();
+    });
+
+    it('resetUserScopedState clears a custom GIF avatar', () => {
+      let state = reducer(undefined, setCustomMascotGifUrl('https://example.com/avatar.gif'));
+      state = reducer(state, resetUserScopedState());
+      expect(state.customMascotGifUrl).toBeNull();
+    });
+
+    const rehydrate = (key: string, payload?: unknown) => ({ type: REHYDRATE, key, payload });
+
+    it('restores a valid persisted custom GIF avatar', () => {
+      const state = reducer(
+        undefined,
+        rehydrate('mascot', { customMascotGifUrl: 'https://example.com/avatar.gif' })
+      );
+      expect(state.customMascotGifUrl).toBe('https://example.com/avatar.gif');
+    });
+
+    it('scrubs an invalid persisted custom GIF avatar back to null', () => {
+      const state = reducer(
+        undefined,
+        rehydrate('mascot', { customMascotGifUrl: 'https://example.com/avatar.svg' })
+      );
+      expect(state.customMascotGifUrl).toBeNull();
+    });
+  });
 });
diff --git a/app/src/store/index.ts b/app/src/store/index.ts
index 532f0fa88..1b5a65edd 100644
--- a/app/src/store/index.ts
+++ b/app/src/store/index.ts
@@ -128,12 +128,14 @@ const persistedNotificationReducer = persistReducer(notificationPersistConfig, n
 const threadPersistConfig = { key: 'thread', storage, whitelist: ['selectedThreadId'] };
 const persistedThreadReducer = persistReducer(threadPersistConfig, threadReducer);
 
-// Mascot appearance + voice — color and voiceId preferences are per-user
-// so they travel with the account on logout/login rather than leaking
-// across users. `voiceId` is the user's chosen ElevenLabs voice for
-// reply speech (issue #1762); `null` falls back to the build-time
-// default in `app/src/utils/config.ts::MASCOT_VOICE_ID`.
-const mascotPersistConfig = { key: 'mascot', storage, whitelist: ['color', 'voiceId'] };
+// Persist only previously persisted mascot appearance fields plus the custom
+// GIF override added by this feature; leave existing non-persisted mascot
+// fields as runtime state to avoid changing refresh behavior.
+const mascotPersistConfig = {
+  key: 'mascot',
+  storage,
+  whitelist: ['color', 'voiceId', 'customMascotGifUrl'],
+};
 const persistedMascotReducer = persistReducer(mascotPersistConfig, mascotReducer);
 
 export const store = configureStore({
diff --git a/app/src/store/mascotSlice.ts b/app/src/store/mascotSlice.ts
index 3c5902023..86be64fbf 100644
--- a/app/src/store/mascotSlice.ts
+++ b/app/src/store/mascotSlice.ts
@@ -38,6 +38,7 @@ export const DEFAULT_MASCOT_VOICE_GENDER: MascotVoiceGender = 'male';
  * is dropped at the reducer boundary.
  */
 export const MAX_MASCOT_VOICE_ID_LEN = 128;
+export const MAX_CUSTOM_MASCOT_GIF_URL_LEN = 2048;
 
 /**
  * Loose shape check for a stored mascot voice id. Issue #1762 lets users
@@ -57,6 +58,27 @@ function isMascotVoiceId(value: unknown): value is string {
   );
 }
 
+function hasGifPath(value: string): boolean {
+  const [path = ''] = value.split(/[?#]/, 1);
+  return path.toLowerCase().endsWith('.gif');
+}
+
+export function isCustomMascotGifUrl(value: unknown): value is string {
+  if (typeof value !== 'string') return false;
+  const trimmed = value.trim();
+  if (trimmed.length === 0 || trimmed.length > MAX_CUSTOM_MASCOT_GIF_URL_LEN) return false;
+
+  try {
+    const parsed = new URL(trimmed);
+    if (!hasGifPath(parsed.pathname)) return false;
+    if (parsed.protocol === 'https:' || parsed.protocol === 'file:') return true;
+    if (parsed.protocol !== 'http:') return false;
+    return ['localhost', '127.0.0.1', '::1', '[::1]'].includes(parsed.hostname);
+  } catch {
+    return hasGifPath(trimmed) && (trimmed.startsWith('/') || trimmed.startsWith('~/'));
+  }
+}
+
 function isMascotVoiceGender(value: unknown): value is MascotVoiceGender {
   return value === 'male' || value === 'female';
 }
@@ -96,6 +118,12 @@ export interface MascotState {
    * persisted blob bounded.
    */
   selectedMascotId: string | null;
+  /**
+   * User-supplied animated avatar source. Kept as a plain validated
+   * string so the renderer can fall back to YellowMascot whenever the
+   * override is absent or scrubbed during rehydrate.
+   */
+  customMascotGifUrl: string | null;
 }
 
 const initialState: MascotState = {
@@ -104,6 +132,7 @@ const initialState: MascotState = {
   voiceGender: DEFAULT_MASCOT_VOICE_GENDER,
   voiceUseLocaleDefault: false,
   selectedMascotId: null,
+  customMascotGifUrl: null,
 };
 
 function isMascotColor(value: unknown): value is MascotColor {
@@ -132,10 +161,23 @@ const mascotSlice = createSlice({
       }
       if (isMascotVoiceId(action.payload)) {
         state.selectedMascotId = action.payload.trim();
+        state.customMascotGifUrl = null;
       } else {
         state.selectedMascotId = null;
       }
     },
+    setCustomMascotGifUrl(state, action: PayloadAction<string | null>) {
+      if (action.payload == null) {
+        state.customMascotGifUrl = null;
+        return;
+      }
+      if (isCustomMascotGifUrl(action.payload)) {
+        state.customMascotGifUrl = action.payload.trim();
+        state.selectedMascotId = null;
+      } else {
+        state.customMascotGifUrl = null;
+      }
+    },
     /**
      * Set or clear the user-selected mascot voice id. Whitespace is
      * trimmed; empty / oversize / non-string values clear the override
@@ -179,6 +221,7 @@ const mascotSlice = createSlice({
           voiceGender?: unknown;
           voiceUseLocaleDefault?: unknown;
           selectedMascotId?: unknown;
+          customMascotGifUrl?: unknown;
         };
       };
       if (rehydrateAction.key !== 'mascot') return;
@@ -191,6 +234,14 @@ const mascotSlice = createSlice({
           : isMascotVoiceId(restoredSelectedMascotId)
             ? (restoredSelectedMascotId as string).trim()
             : null;
+      const restoredCustomMascotGifUrl = rehydrateAction.payload?.customMascotGifUrl;
+      state.customMascotGifUrl =
+        restoredCustomMascotGifUrl == null
+          ? null
+          : isCustomMascotGifUrl(restoredCustomMascotGifUrl)
+            ? (restoredCustomMascotGifUrl as string).trim()
+            : null;
+      if (state.customMascotGifUrl) state.selectedMascotId = null;
       // `voiceId` is optional in older persisted blobs (pre-#1762) — the
       // `null` fallback is the intended default and matches a fresh
       // install. Invalid values are scrubbed so a corrupted localStorage
@@ -220,6 +271,7 @@ export const {
   setMascotVoiceGender,
   setMascotVoiceUseLocaleDefault,
   setSelectedMascotId,
+  setCustomMascotGifUrl,
 } = mascotSlice.actions;
 
 export const selectMascotColor = (state: { mascot: MascotState }): MascotColor =>
@@ -237,6 +289,9 @@ export const selectMascotVoiceUseLocaleDefault = (state: { mascot: MascotState }
 export const selectSelectedMascotId = (state: { mascot: MascotState }): string | null =>
   state.mascot.selectedMascotId;
 
+export const selectCustomMascotGifUrl = (state: { mascot: MascotState }): string | null =>
+  state.mascot.customMascotGifUrl;
+
 /**
  * Resolve the voice id the next reply will be synthesised with, taking
  * into account every mascot-voice setting plus the active locale. This