Mr. singular and my best friend at work tell me I’m the middle-aged version of George from Dead Like Me. I know when I was her age I was exactly her, so I gotta agree with them.
I’m slowly aging (well, I guess actually at the same rate as everyone else) into Prof. Hubert J. Farnsworth.
Please tell us you have pictures of you holding a machine gun!
I’d say I’m an older version of Season1-3 Willow Rosenberg, with a little Radar O’Reilly thrown in for good measure.
StG
I just started catching old reruns of CSI, and I couldn’t help but notice a surprising bit of resemblence to Gil Grissom.
That’s on a good day, anyway. On a bad day, I think I’m Cobra Commander when he’s at his best.
For a while there, I was Adrian Mole, age 13 1\2. Then I was Barney Fife for a brief period, and if I don’t get my hair cut soon, I’ll be Jim from Taxi.
I’m equal parts Jim Rockford, Arthur Dietrich, and Alex Rieger.
All of my friends tell me that I’m Karen from “Will and Grace”.
I’ll agree! 
Well, I came in to claim Adrian Monk, I used to be Radar O’Reilly, but really…
I’m the teacher from ‘Beavis and Butthead’.
I’ve been told the resemblance to Agent Dana Scully is uncanny…
I am Mr Bentley from “The Jeffersons”, or Shaggy from “Scooby Doo”.
Just yesterday, while watching some ads for an upcoming show, my husband said the Leah Remini character sounded just like me. :rolleyes:
Split personality, eh? 
I used to be a mix of Sam Malone and David Puddy. Now it’s all Hank Hill.
I am the spitting image of Miranda from Sex in the City. Well, if she were heavy. We look alike and are very much alike in personality, though I think she is a skosh more judgemental than I am most of the time.
Heh. You mean Willow from Buffy, right? I’ve never watched it. I keep meaning to, but there’s just so much of it…
I’ve frequently been called Giles, and even been honoured with it as a title (as in “you are my Giles!”). Apparently it’s the combination of being tall, bespectacled and motherly while randomly blurting facts on forteana and the occult.
And yes, one of my hobbies is cross-referencing.
ETA: Erm… I was going to add something but lost my train of thought. Nevermind.
In my own mind, I’m any one of those sitcom fat slobs who lucked into marrying a hottie.
To my kids, I’m sometimes Red Foreman and sometimes Homer Simpson.
My wife sees a lot of Victor Meldrew and a little of Adrian Monk in my personality.
I am what House would be if he was uneducated and could manage pain better. But I have his intelligence & intuition combined with an abrasive & addictive personality. I find most people annoying and frustrating. “If A=B and B=D and D=C, why can’t you just grasp that A=C dammit?”
I’m kind of a blend of Chandler (witty) and Ross (nerdy/intellectual) from Friends.