A tall, lanky actor who honed his craft on stage before hitting his stride as a character actor in films and TV, John C. McGinley was born in NYC's Greenwich Village and raised in Millburn, New Jersey. Shortly after earning his MFA from NYU, he landed his first professional gig as John Turturro's understudy in John Patrick Shanley's Off-Broadway play "Danny and the Deep Blue Sea". When Turturro took a couple of weeks off to shoot a film, McGinley assumed the role and was spotted by a talent scout who recommended the young performer to director Oliver Stone. Stone in turn cast McGinley in his Vietnam drama "Platoon", although it would be over a year before the project saw fruition. In the meantime, the actor continued to appear in theatrical production, including the short-lived 1985 Broadway mounting of "Requiem for a Heavyweight".

By the time Stone had worked out the problems and "Platoon" went before the cameras, McGinley had already made his film debut in "Sweet Liberty" (1986). When actor John Spencer had to withdraw from the war film, Stone cast McGinley in the role of the sycophantic Sgt. O'Neill, inaugurating a multi-film collaboration that encompassed "Wall Street" (1987, as a jealous co-worker of lead Charlie Sheen), "Talk Radio" (1988, with McGinley recreating his stage role as the station engineer) and "Born on the Fourth of July" (1989). The latter, however, proved logistically problematic and caused something of a rift between actor and director. When Stone offered him a role, McGinley faced a logistical nightmare as he already was committed to "Fat Man and Little Boy" (also 1989). Because he of the schedule troubles, he had what amounted to a cameo in "Born on the Fourth of July" and it was six years before he and Stone would work together on "Nixon" (1995).

Despite the minor contretemps with Stone, McGinley did not go begging for work. He remained a busy character player in efforts ranging from the underrated WWII drama "A Midnight Clear" to the ill-advised in "Car 54, Where Are You?" (1993) to his sterling turns as psychopathic killers in the Fox miniseries "Dean Koontz's Intensity" (1997) and "Dean Koontz's Sole Survivor" (2000). The actor won a new set of fans when he was cast as the creatively insulting, professionally demanding but far from heartless Dr. Perry Cox on the NBC sitcom "Scrubs" (2001- ), a role that would prove defining in the actor's career by providing a showcase for his diverse comedic and dramatic skills.