john christopher mcginley (born august 3, 1959) is an american actor, comedian, spokesperson, and writer. he is known for his roles as perry cox in "scrubs", bob slydell in "office space", sergeant red o'neill in oliver stone's "platoon" and marv in stone's "wall street". he has also written and produced for television and movies. mcginley is also an author and a spokesperson for the national down syndrome society.