Doctor Jonathan Micheael "J.D." Dorian is the main character and narrator of Scrubs and is played by Zach Braff.  J.D. is best friends with Turk, who he's been friends with since they were roommates in college.  J.D. quickly meets Elliot, who he falls for hard and has an on and off again relationship with throughout the series. 

J.D.'s mentor is Dr. Cox who he is constantly trying to impress without making much headway.  He also has a bitter rival at Sacred Heart who torments him endlessly... The Janitor.  J.D. frequently daydreams where he tilts his head to the side and drifts away.

J.D. Quotes

Ben: Hey J.D. My sister Danni is more of a gentle kisser, don't you think? But I find Jordan is loaded more along the lines of teeth and tongue.
J.D.: Would you please stop it?
Ben: Fangs.

J.D.: When you get back from surgery, Mrs. Grodberg, we'll play Scrabble again, and this time I'll beat you!
Dr. Kelso: Well of course you'll beat her son, she's having half her brain removed!

Scrubs Quotes

J.D.: We found you in the park throwing rocks at old couples...
Ted: Why should they be happy!?

J.D.'s Thoughts: Wait, is she in to me? Quick, make a bad joke and see if she laughs.
J.D.: Did you hear the one about the skeleton who couldn't go to the party? He had no body to go with.
Neena: That's really funny!
J.D.'s Narration: Well that's not a fair test - that joke's hilarious.