I find Dave Foley depressing so pretty much anything he plays... Joe Matt, Art Spiegelman's dad in Maus...I guess those are real...
Garfield's owner, eeyore, every rabbit that leaves the warren in watership down, Spaulding Grey in "Drunks", Kunta Kinte, the mom in Requiem for a Dream, Ali from Ali: Fear Eats the Soul, the Elephant Man, the kid in Grave of the Fireflies, chance the Gardener, Mr. Joyboy from the Loved One...
my #1 pick though is the donkey Balthazar from Au Hasard Balthazar