Gained fame as Sullivan Groff on Showtime's Weeds and as Dr. Brenner in Netflix's Stranger Things. He's also known for his roles as a disturbed Vietnam vet in Birdy and Private Joker in Full Metal Jacket.
He appeared in John Sayles's Baby It's You for his first professional acting role.
He earned Golden Globe nominations for his roles in the TV miniseries And the Band Played On and What the Deaf Man Heard.
He was raised by his parents, bookkeeper Dolores Modine and the drive-in theater manager Mark Alexander. He married Caridad Rivera in 1980 and he has two kids named Boman and Ruby.
He is an award-winning American actor who worked with Stanley Kubrick on Full Metal Jacket.