Natural within Youngstown, Ohio, O'Neill attended Ursuline High School. He continued to Youngstown State University and was a sales person football player for the Pittsburgh Steelers and social studies teacher before becoming an actor. He has appeared around many motion picture, including The Bone Collector, Dutch, and a ''Wayne's World series.

Besides his role in Married... heavy'', more notability television role of O'Neill's is when a reincarnation of Sgt. Joe Friday in Dick Wolf's brief remake of Jack Webb's classic TV crime series, Dragnet. Piece Married... lasted for x years (1987-1997), Dragnet lasted simply ii half-seasons.

He got short cameos within Wayne's World and its sequel, reprising the menacing character he played during the Wayne's World sketch on Saturday Night Live.

Presently, O'Neill appears as a recurring character on NBC's The West Wing playing Gov. Eric Baker (D-PA), who was considered the likely Vice Presidential candidate.

O'Neill is married to actress Catherine Rusoff.

Trivia
Ed was drafted per Pittsburgh Steelers in 1969 but was cut in step by step training camp.