Gordon Freeman - Half-Life
Umm... I like Gordon Freeman, but he is a mute protagonist with no defined personality. He is just the player.
Speaking or having a defined personality are not requirements of this list. The only requirement is that the protagonist be *memorable* and it's hard to argue that Gordon Freeman isn't.
The fact that he was a blank slate for the player to project onto within the scope of the phenomenal HL universe is a large part of what makes him so memorable in the first place.