diff --git a/lib/shared/avatar-utils.js b/lib/shared/avatar-utils.js
--- a/lib/shared/avatar-utils.js
+++ b/lib/shared/avatar-utils.js
@@ -1,9 +1,14 @@
 // @flow
 
+import invariant from 'invariant';
 import stringHash from 'string-hash';
 
 import { selectedThreadColors } from './thread-utils.js';
+import { threadInfoSelector } from '../selectors/thread-selectors.js';
 import type { ClientEmojiAvatar, ClientAvatar } from '../types/avatar-types.js';
+import { type ThreadType, threadTypes } from '../types/thread-types.js';
+import { useResolvedOptionalThreadInfo } from '../utils/entity-helpers.js';
+import { useSelector } from '../utils/redux-utils.js';
 
 const defaultAnonymousUserEmojiAvatar: ClientEmojiAvatar = {
   color: selectedThreadColors[4],
@@ -57,4 +62,52 @@
   return getDefaultAvatar(user.username);
 }
 
-export { getAvatarForUser };
+function useGetAvatarForThread(
+  thread: ?{
+    +id: string,
+    +type: ThreadType,
+    +avatar?: ?ClientAvatar,
+    +color: string,
+    +parentThreadID: ?string,
+    ...
+  },
+): ClientAvatar {
+  const viewer = useSelector(state => state.currentUserInfo);
+
+  const parentThreadID = thread?.parentThreadID;
+  const parentThreadInfo = useSelector(state =>
+    parentThreadID ? threadInfoSelector(state)[parentThreadID] : null,
+  );
+  const resolvedParentThreadInfo =
+    useResolvedOptionalThreadInfo(parentThreadInfo);
+
+  if (!thread) {
+    return defaultAnonymousUserEmojiAvatar;
+  }
+
+  if (thread.avatar) {
+    return thread.avatar;
+  }
+
+  if (thread.type === threadTypes.SIDEBAR) {
+    invariant(
+      resolvedParentThreadInfo,
+      'parentThreadInfo should be set for sidebars',
+    );
+
+    return resolvedParentThreadInfo.avatar
+      ? resolvedParentThreadInfo.avatar
+      : getDefaultAvatar(
+          resolvedParentThreadInfo.id,
+          resolvedParentThreadInfo.color,
+        );
+  }
+
+  if (thread.type === threadTypes.PRIVATE) {
+    return getAvatarForUser(viewer);
+  }
+
+  return getDefaultAvatar(thread.id, thread.color);
+}
+
+export { getAvatarForUser, useGetAvatarForThread };
diff --git a/lib/types/thread-types.js b/lib/types/thread-types.js
--- a/lib/types/thread-types.js
+++ b/lib/types/thread-types.js
@@ -2,6 +2,7 @@
 
 import invariant from 'invariant';
 
+import type { ClientAvatar } from './avatar-types.js';
 import type { Shape } from './core.js';
 import type { CalendarQuery, RawEntryInfo } from './entry-types.js';
 import type { Media } from './media-types.js';
@@ -212,6 +213,7 @@
   +type: ThreadType,
   +name: ?string,
   +uiName: string | ThreadEntity,
+  +avatar?: ?ClientAvatar,
   +description: ?string,
   +color: string, // hex, without "#" or "0x"
   +creationTime: number, // millisecond timestamp
@@ -230,6 +232,7 @@
   +type: ThreadType,
   +name: ?string,
   +uiName: string,
+  +avatar?: ?ClientAvatar,
   +description: ?string,
   +color: string, // hex, without "#" or "0x"
   +creationTime: number, // millisecond timestamp