Education
O'Neill studied at Syracuse University.
O'Neill studied at Syracuse University.
He served in the Navy then returned to the theater. In the late 1950s, he began appearing on television. He was probably best known for his role as Charlie Cagney in the television hit Cagney & Lacey.
Before moving to California, he appeared on the Broadway stage in such hits as Promises, Promises, The Unsinkable Molly Brown, and Skyscraper. His film credits include The Mugger (1958), To the Shores of Hell (1966), Gammera the Invincible (1966), Pretty Poison (1968), Some of My Best Friends Are. (1971), The Taking of Pelham One Two Three (1974), The Front Page (1974), Posse (1975), St. Ives (1976), American Raspberry (1977), MacArthur (1977), The Buddy Holly Story (1978), House Calls (1978), The Jerk (1979), Wolfen (1981), Chiller (1985), Prizzi's Honor (1985), The Mosquito Coast (1986), She's Out of Control (1989) and Loose Cannons (1990).
On November 17, 1998, O'Neill died at the age of 70 at St. John's Medical Center in Santa Monica.
He began his acting career as an original company member of Arena Stage in Washington, D.C.
