I'm on the JD = INFP train. He does stuff, but always deciding and fantasizing and narrating in his head!
Agree bolded:
Turk - ESFP
Dr. Cox - ENTP
Dr. Cox's wife/former ex/whatever - xSTP
Elliot - ESFJ
Janitor - ISTP
Carla - ISFJ
Kelso - ESTJ
Lawyer - ISxJ
I think Dr. Cox is more xSTP. He's very... physical, in the way he conducts himself and his aggression. Seems very SP to me, not the intellectual-ish-ness of an NT.
Jordan/Dr.Cox's wife: I can see ESTP, but I'm equally torn between ESTP and ENTJ. Hmmmm, she's diabolical, but in a self-entertainment manner.
Carla: I think ESFJ. (instead of ISFJ) Up in people's business a lot- and seems energized by it in a natural-mode thing. But I'm not super-sure.
Elliot and Janitor: I have no idea. Well, I think it's pretty safe to say the Janitor is an I. But he and JD have this whole fantasy world thing together almost. Certainly Janitor has a very warped sense of humor and wild fantasies he makes up to lie to people. But should we consider how he acts to JD how he acts to the world as a whole. I suppose in the beginning he only acted with JD in that manner, but as the show has gone on, he's interacted more and more crazy with all the characters.
Elliot, hmmm. I think she started as an ESTJ. Very driven and somewhat ruthless. But I can see the ESFJ.