diff --git a/app/assets/javascripts/discourse/helpers/bound-avatar.js.es6 b/app/assets/javascripts/discourse/helpers/bound-avatar.js.es6
index 2833f8cefb1..43cea519d48 100644
--- a/app/assets/javascripts/discourse/helpers/bound-avatar.js.es6
+++ b/app/assets/javascripts/discourse/helpers/bound-avatar.js.es6
@@ -1,5 +1,6 @@
 import { htmlHelper } from 'discourse-common/lib/helpers';
 import { avatarImg } from 'discourse/lib/utilities';
+import { classesForUser } from 'discourse/helpers/user-avatar';
 
 export default htmlHelper((user, size) => {
   if (Ember.isEmpty(user)) {
@@ -7,5 +8,10 @@ export default htmlHelper((user, size) => {
   }
 
   const avatarTemplate = Em.get(user, 'avatar_template');
-  return avatarImg({ size, avatarTemplate });
+  let args = { size, avatarTemplate };
+  let extraClasses = classesForUser(user).join(' ');
+  if (extraClasses && extraClasses.length) {
+    args.extraClasses = extraClasses;
+  }
+  return avatarImg(args);
 });
diff --git a/app/assets/javascripts/discourse/helpers/user-avatar.js.es6 b/app/assets/javascripts/discourse/helpers/user-avatar.js.es6
index 71e6e87249c..8054631dfab 100644
--- a/app/assets/javascripts/discourse/helpers/user-avatar.js.es6
+++ b/app/assets/javascripts/discourse/helpers/user-avatar.js.es6
@@ -1,6 +1,23 @@
 import { registerUnbound } from 'discourse-common/lib/helpers';
 import { avatarImg, formatUsername } from 'discourse/lib/utilities';
 
+let _customAvatarHelpers;
+
+export function registerCustomAvatarHelper(fn) {
+  _customAvatarHelpers = _customAvatarHelpers || [];
+  _customAvatarHelpers.push(fn);
+}
+
+export function classesForUser(u) {
+  let result = [];
+  if (_customAvatarHelpers) {
+    for (let i=0; i<_customAvatarHelpers.length; i++) {
+      result = result.concat(_customAvatarHelpers[i](u));
+    }
+  }
+  return result;
+}
+
 function renderAvatar(user, options) {
   options = options || {};
 
diff --git a/app/assets/javascripts/discourse/initializers/banner.js.es6 b/app/assets/javascripts/discourse/initializers/banner.js.es6
index 9c9ff47d927..1e9695d081e 100644
--- a/app/assets/javascripts/discourse/initializers/banner.js.es6
+++ b/app/assets/javascripts/discourse/initializers/banner.js.es6
@@ -1,11 +1,11 @@
 import PreloadStore from 'preload-store';
+import { withPluginApi } from 'discourse/lib/plugin-api';
 
 export default {
   name: "banner",
   after: "message-bus",
 
   initialize(container) {
-
     const banner = Em.Object.create(PreloadStore.get("banner")),
           site = container.lookup('site:main');
 
diff --git a/app/assets/javascripts/discourse/lib/plugin-api.js.es6 b/app/assets/javascripts/discourse/lib/plugin-api.js.es6
index 60fc1233a58..bc15c489529 100644
--- a/app/assets/javascripts/discourse/lib/plugin-api.js.es6
+++ b/app/assets/javascripts/discourse/lib/plugin-api.js.es6
@@ -23,9 +23,10 @@ import { addNavItem } from 'discourse/models/nav-item';
 import { replaceFormatter } from 'discourse/lib/utilities';
 import { modifySelectKit } from "select-kit/mixins/plugin-api";
 import { addGTMPageChangedCallback } from 'discourse/lib/page-tracker';
+import { registerCustomAvatarHelper } from 'discourse/helpers/user-avatar';
 
 // If you add any methods to the API ensure you bump up this number
-const PLUGIN_API_VERSION = '0.8.17';
+const PLUGIN_API_VERSION = '0.8.18';
 
 class PluginApi {
   constructor(version, container) {
@@ -368,6 +369,23 @@ class PluginApi {
     appEvents.on(name, fn);
   }
 
+  /**
+    Registers a function to generate custom avatar CSS classes
+    for a particular user.
+
+    Takes a function that will accept a user as a parameter
+    and return an array of CSS classes to apply.
+
+    ```javascript
+    api.customUserAvatarClasses(user => {
+      if (Ember.get(user, 'primary_group_name') === 'managers') {
+        return ['managers'];
+      }
+    });
+   **/
+  customUserAvatarClasses(fn) {
+    registerCustomAvatarHelper(fn);
+  }
 
   /**
    * Changes a setting associated with a widget. For example, if