Perry cox

Dr. Cox is the senior attending physician at Sacred Heart Hospital and Residency Director for the hospital. In a 2003 episode, it is established that he is 40 years old, which probably places his birth somewhere around 1963. However, in "My Growing Pains", which aired in 2007, he states his age at a more specific 47, making his birth year closer to 1960, within a year of McGinley's true birth date. He is the sarcastic, bitter mentor of John "J.D." Dorian, the show's main character. Dr. Cox routinely rants at and belittles J.D., though his rough treatment of J.D. is intended as conditioning for the rigors and horrors of hospital life, as well as an outlet for Cox's frustration in his own life. It is hinted that he is secretly proud of J.D. and thinks he has the potential to become a great doctor.
Dr. Cox is sarcastic and narcissistic, with a quick, cruel wit. He is also very concerned about the way he is perceived in the hospital, often making very illogical and self-destructive decisions in order to keep his "bad boy" image. He works out extensively and thus is physically fit; he shows off his physique to women by lounging around his apartment shirtless. In "My Sacrificial Clam", he says that the "key to my exercise program is this one simple truth: I hate my body."
Even though he often complains about his job and calls Sacred Heart a "dump", it is often implied that work is one of the only things he truly loves. In the episode "My Bad", his ex-wife Jordan Sullivan challenges him to name three places other than his apartment and the hospital that he has been in the past month, to which he answers "my car". In "My Fallen Idol", Kelso tells him to accept that he needs to be needed.
He uses nicknames for most of the other main characters on the show: he calls J.D. "Newbie" and a vast assortment of girls' names, Chris Turk is "Gandhi" and "Turtle Head" and, most recently, "Gandidiot", Dr. Bob Kelso is "Bobbo" and sometimes "Bobcat", "Beelzebob" and even once "The Bobbotron", pathologist Doug Murphy is "Nervous Guy" or "Pee Pants", Sacred Heart legal counsel Ted Buckland is "Flop Sweat" or "Sweaty Teddy", Janitor is "Stretch", "Jumpsuit", "Super-cuts", and "Lurch", and Elliot Reid is "Barbie" and "Blondie." The only member of the main cast he always calls by her actual name is Carla Espinosa ,a staff nurse.