Not really fan art, per se.. but.. I figure some here might get the same kick out of this that I did when I first saw it a year or so ago.
A skin for Bill Rizer from Contra, made to look like Doomguy (using Contra 3 sprites as a base). Made for Super Mario Bros. Crossover. Skin is currently NOT in-game.
And if it did get included, I doubt the portrait would animate as proposed.. they're just put there because those spaces are otherwise empty.
Credits:
Frozsoul for making the original skin and allowing me to update it
Me for updating it in numerous places
Belial the Hedgehog for the Contra 3 sprite rips
..and, of course, Konami and id Software