MyBB favicon code for your forum without a plugin, how to add a favicon for MyBB.
Favicons are little cool images that displays in the web browser’s tab and address bar while viewing the website, and while they serve no useful purpose, adding a MyBB favicon adds a personal touch to any MyBB forum website. Here you’ll see how to add a MyBB favicon code without the need for a plugin, just one piece of code and a favicon image is all you need.
1. Create your MyBB favicon for your MyBB forum, it should be 16×16 and saved as a .ico image.
2. Upload it to your forum’s root folder (whever you installed your MyBB forum)
3. Login to your forum and go to Admin CP > Templates & Style > Templates/Template Sets > Default Templates > Ungrouped Templates > headerinclude.
4. Under this code…
<link rel="alternate" type="application/rss+xml" title="{$lang->latest_threads} (RSS 2.0)" href="{$mybb->settings['bburl']}/syndication.php" />
<link rel="alternate" type="application/atom+xml" title="{$lang->latest_threads} (Atom 1.0)" href="{$mybb->settings['bburl']}/syndication.php?type=atom1.0" />
Add this:
<link rel="shortcut icon" type="image/x-icon" href="/yourimagename.ico">
Save changes.
You should now see your new MyBB favicon code in your forum, if not then wait a few hours for the changes to take full effect on your forum’s server.
If you have other template sets besides the Default Templates, you can have different favicons with each template set for more added customizations to your forum.

Thanks! I was looking for a code instead using a Plugin!
Thanks! Really easy to install.