He is best known for his roles in Let's Scare Jessica to Death (1971), Bogie (1980) and The Brink's Job (1978).
He moved to New York City for his career, where he appeared in Broadway productions as an actor, as well as direct and teach.
O'Connor also appeared on television in Hawaii Five-O, in October 1969 as security guard Jim Crawford in The Doctors and Tales from the Darkside as well as several television movies.
He portrayed Humphrey Bogart in the 1980 biographical television movie Bogie.
He lived at the Hotel Chelsea in New York City and died there at the age of 56 on June 22, 1991.