Rick and Morty in Dragon's Dogma: Dark Arisen (source)
When artists go looking for inspiration for their artwork they often look at pics of famous folks, real or imaginary, since their faces are recognizable and have bold features which makes them great reference material.
Abraham Lincoln in Fallout 4 (source)
But there's one main problem with using famous faces as reference material- they're recognizable, and therefore any little mistake in the makeup of their face becomes glaringly obvious in your artwork.
When game artists tried to add Steve Buscemi's face to a character in Saints Row IV he came out looking more like Steve's cousin Sal, who has a bit of a drinking problem. But this Dwight Schrute from Saints Row the Third is spot on!
And even though he has a face many people want to punch you've gotta admit Guy Fieri does make a great model for video game characters, but what's with that weird baby head thing from Dark Souls 3? *shiver*