Commander Shepard from Mass Effect.
Yes, I said it.
He's nothing more than an avatar for the player and on his own terms he utterly fails as a character, in fact he's probably one of the great non characters. When he converses with other characters it's THEM who do all the actual talking, all HE does is ask them questions.
Plus the way he flirts with some female characters seems more like grounds for being sued for sexual harrassment.
Don't get me wrong, he's still okay as these things go and I admit that I enjoy role playing in the Mass Effect universe. But I'm also not going to kid myself about Shepard as a character on his own terms.
After a while you have to notice that Shepard doesn't emote, he's just kind of a brick. The worst example of boneheaded emotionless dialogue for me personally was on Horizon where he finally reuinites with his star crossed lover Ashley Williams, they hug and she's all but about to break into tears after the two years of grief after his 'death'. He then opens with the brilliant line:
"It's good to see you Williams, how've you been?"
Seriously, great way to greet someone who loved you and spent two years in grief. Well done.
The badass ultra cool dude who sleeps with all the chicks and kills giant space robot cuttlefish is basically just a fourteen year old's interpretation of what is otherwise a total blank slate with no identity, personality or even set backstory.
He's just a blank slate that happens to have a lot of dialogue options.
EDIT: By the way for all the people talking about Masterchief:
He blew up the Halo intallation.
He grabbed a bomb, carried it out with him after jumping out of a space station in the middle of a fleet battle to plant said bomb onto an enemy frigate.
He killed the Prophet of Regret.
He destroyed the entire flood infection by activating a Halo ring in a zone beyond the rim of our galaxy and subsequently destroyed the Ark as well.
I'm just saying, dude's done stuff.