Well, Malcom Reynold's Revolver is not a pistol (which also disqualifies the Taurus Judge), so I would like to say Alucard's handgun from Hellsing...no wait, the LX-18 with a scope has a special place in my heart. I have no idea why, it's not very powerful, it's not iconic or unique looking, but whenever someone says "Think of a pistol" that's the one that immediately jumps to mind. I guess the Glock 18 is cool too, seeing how it's fully automatic. But then again...that classifies it as a machine pistol along with Uzi's and Mac's. Pretty sure the Tec-9 is classed as a sub-machine gun and that I'm getting way off topic.
So, I wanted to say Maria from New Vegas, because of the barrel carvings, but I don't now because I never saw the handle in-game and it makes me uneasy.
And while the LX-18 is great, it's not iconic and not worth your time (but I'll leave a link anyway.) http://timesplitters.wikia.com/wiki/LX-18
And the Mauser is just a gun, I've never seen it used by anyone special so...Walther P2K. 007 Nightfire. Final answer. Unless you can make one glow, in which case you should make a Maliwan handgun. The ones from the second game glow so good.
EDIT: How could I forget. The flintlock pistol from Fable. Flintlocks are awesome. Do that one.