As of July 2026, Michael O'Neill is best known for Grey's Anatomy and NCIS. Find every show and movie Michael O'Neill has starred in — and where to watch them — below.
Michael O'Neill

Michael O'Neill

Actor Born 1947 Montgomery, Alabama, USA 12 TV Shows 8 Movies

​From Wikipedia, the free encyclopedia.

Michael O'Neill (born May 29, 1951) is an American actor. With a career stretching through three decades, he usually portrays senior law enforcement or military officers. He is perhaps best known for his role as Special agent Ron Butterfield, the head of President Josiah Bartlet's Secret Service detail, on The West Wing. He played CTU Administrative Director Richard Walsh in the first two episodes of 24. He played Sgt. Maj. Ron Cheals in the CBS action-drama series The Unit. He starred in the Season Six 2 part Finale of Grey's Anatomy as the broken widower who holds the hospital hostage with a 9mm while pursuing the doctors responsible for unplugging his wife. His most notable film performances occur in Seabiscuit, Secondhand Lions, Transformers, Dancer, Texas Pop 81, Traffic, Sea of Love, A Quiet Little Marriage, Nothing But the Truth, and Green Zone. O'Neill graduated from Auburn University in 1974. After attending Auburn he spent time under the tutelage of actor Will Geer and his daughter, Ellen, at Theatricum Botanicum in Los Angeles before moving to New York to pursue his career there.

Michael O'Neill's screen work to date leans strongly toward Drama and Crime, a consistent thread across his credits so far.

Michael O'Neill's most notable role to date came in Transformers (2007), where he played Tom Banacheck. He also appeared in Grey's Anatomy (2005) as Gary Clark. Most recently appeared in Dallas Buyers Club (2013) as Richard Barkley.

Fans wanting to catch up on Michael O'Neill's work can find exactly where his shows and movies are streaming below — and TV Butler Pro makes it effortless to keep track of them all. Just search the title, and Butler finds it instantly, tells you which service has it, and remembers what you've already watched.

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📺 Michael O'Neill's TV Shows

Grey's Anatomy
Gary Clark
2005
NCIS
Riley McCallister
2003
S.W.A.T.
Carl Luca
2017
The West Wing
Ron Butterfield
1999
Tom Clancy's Jack Ryan
Senator Mitchell Chapin
2018
Army Wives
Reverend Bankerd
2007
Scandal
Lonnie Mencken
2012
The Unit
Ron Cheals
2006
Bates Motel
Nick Ford
2013
Boston Public
Dr. Bernard Colbert
2000
Shooter
Ray Brooks
2016
Extant
Alan Sparks
2014

🎬 Michael O'Neill's Movies

War of the Worlds
Secretary of Defense Walter Crystal
2025
Dallas Buyers Club
Richard Barkley
2013
Bride Hard
Frank
2025
Traffic
Lawyer Rodman
2000
Transformers
Tom Banacheck
2007
Air
Joe Dean
2023
Seabiscuit
Mr. Pollard
2003
Sea of Love
Raymond Brown
1989

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