John Marston: Yes
Jerry Seinfeld: Yes
Let's try a hard one...
Daniel from Amnesia: Holy fucking shit, he got it.
Captain Price: Yep
Agent 47: Yes
Gordon Freeman: Yes
The Heavy: Yes
Michael Scott: Yes
Niko Bellic: Yeah, but after 3 tries
Donnie Darko: Yes
Time for another hard one...
Fawkes from FO3: Yes!
Artyom: Yes
'Nother hard one
Frank Bilders from Far Cry 2: No! I beat it

(Though it did guess Mattias Nilsson which I suppose is close...)
Just for good measure, I'll do a couple more.
The Adoring Fan from Oblivion: Yes :O
Benny from FO:NV: Yes
JC Denton from Deus Ex: Yep
Super Meat Boy: Yes
Vito Scaletta: Yes
Time for the FINAL BOSS:
The Minecraft guy: what the shit man. He got it. And apparently his name is Steve.
EDIT: Whaddya know, he guessed Yahtzee right when I said my character was an adult male who disliked most things and wore a funny hat.