Pretty sure its just Desmond. I imagine when he's unconscious in the Animus after the end of Brotherhood his face doesn't shave itself :P, which easily explains the beard.
Retail 100% - Assassins Creed, Assassins Creed II, Assassins Creed: Brotherhood, Oblivion, Skyrim, Sleeping Dogs, Resident Evil 4
Arcade 100% - Plants vs. Zombies, Minecraft
Currently Playing: Dead Space 3, Far Cry 3, Sleeping Dogs