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

J.D.: Kudos on the nice pooper.
Ron: Thank you.
J.D.: Mine's firm like mutton.
Ron: Lovely.

J.D.: My man Turk, is getting it daily and nightly and ever so rightly! Ah! What up, dogg!
J.D.'s narration: Once every 4.2 seconds a man says something stupid that a woman hears and punishes him for... luckily, this wasn't one of those times.
Carla: What did you just say?
J.D.: "What up...dogg?"

Scrubs Quotes

Perry, what has two thumbs and still doesn't give a crap? Bob Kelso! I thought we'd met.

Dr. Kelso

J.D.: Kudos on the nice pooper.
Ron: Thank you.
J.D.: Mine's firm like mutton.
Ron: Lovely.