Robert Clohessy (born June 10, 1957) is an American actor. He is best known for playing Correctional Officer Sean Murphy on the HBO drama Oz, and Lieutenant Sid Gormley on Blue Bloods.
Clohessy was born in The Bronx, the son of John Clohessy, a police officer. Clohessy graduated from SUNY Purchase, his Oz co-stars Edie Falco, Kirk Acevedo, and Seth Gilliam were also alumni of SUNY Purchase. Clohessy fought in the 1975 Golden Gloves in Madison Square Garden. He graduated from Pearl River High School in Pearl River, New York where he played varsity football. Clohessy first appeared on stage at Pearl River High School in their class production of Kismet, followed by the senior year production of Pajama Game!