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.
TBAWar of the Worlds as Unknown
2025Bride Hard as Frank
2024Happy's Place (2 Episodes) as Jim Jackoway
2023Air as Joe Dean
2022Fire Country (1 Episode) as Harlan Denbo
2022Echoes (7 Episodes) as Victor McCleary
2022Outer Range (2 Episodes) as Judge Pettigrew
2021Cold Call as Christian
2020The Stand at Paxton County as Dell Connelly
2020Messiah (5 Episodes) as Cameron Collier
2019Clemency as Chaplain David Kendricks
2018Indivisible as Chaplain Rogers
2018The Romanoffs (1 Episode) as Ron Hopkins
2018Danger One as Beckwith
2018Tom Clancy's Jack Ryan (5 Episodes) as Senator Mitchell Chapin
2018The Resident (1 Episode) as Joshua Williams
2017S.W.A.T. (3 Episodes) as Carl Luca
2016Shooter (3 Episodes) as Ray Brooks
2016This Is Us (1 Episode) as Arlo
201611.22.63 (1 Episode) as Arliss Price
2014Manhattan (1 Episode) as Psychiatrist
2014Extant (13 Episodes) as Alan Sparks
2014The Grim Sleeper as Detective Simms
2013Dallas Buyers Club as Richard Barkley
2013Rectify (15 Episodes) as Senator Roland Foulkes
2013Bates Motel (8 Episodes) as Nick Ford
2012Scandal (5 Episodes) as Lonnie Mencken
2011J. Edgar as Senator McKellar
2010Law & Order: LA (1 Episode) as Jeb Monroe
2010Rizzoli & Isles (1 Episode) as Jonathan McKnight
2010The Glades (1 Episode) as Trent Staley
2010Green Zone as Colonel Bethel
2009FlashForward (1 Episode) as CIA Director Keller
2009NCIS: Los Angeles (1 Episode) as Ret. U.S. Army General Richard Collins
2008Nothing But the Truth as CIA Director
2008Leverage (1 Episode) as Judge Roy
2008A Quiet Little Marriage as Bruce
2008The Mentalist (1 Episode) as Sheriff Nelson
2008Fringe (1 Episode) as Sheriff Velchik
2008Sons of Anarchy (1 Episode) as Anthony Franklin
2008Crazy as Ralph Christianson
2007Transformers as Tom Banacheck
2006The Nine (3 Episodes) as Pete Burton
2006The Unit (1 Episode) as Ron Cheals
2005Commander in Chief (2 Episodes) as Congressman Wilcox
2005Ghost Whisperer (1 Episode) as Nolan
2005Criminal Minds (1 Episode) as Det. Yarbough
2005Prison Break (1 Episode) as Herb Stanton
2005Grey's Anatomy (4 Episodes) as Gary Clark
2004Around the Bend as Cowboy
2004LAX (1 Episode) as Alonso Mathews
2004American Crime as Sheriff Smyth
2003NCIS (3 Episodes) as Riley McCallister
2003Secondhand Lions as Ralph
2003Seabiscuit as Mr. Pollard
2003Dreamcatcher as General Matheson
2002Without a Trace (1 Episode) as Thomas Shannon
200124 (1, 1 Episode) as Richard Welsh, Richard Walsh
2001Crossing Jordan (1 Episode) as Chris Benz
2000Traffic as Lawyer Rodman
2000The Legend of Bagger Vance as O.B. Keeler
2000Boston Public (4 Episodes) as Dr. Bernard Colbert
1999Roswell (1 Episode) as Philip Evans
1999The West Wing (15 Episodes) as Ron Butterfield
1999ATF as ATF Asst. Director Ben Walker
1999The Mod Squad as Greene
1998Dancer, Texas Pop. 81 as Mr. Lusk
1998Virtual Obsession as Unknown
1998Standoff as Cult Leader (Voice)
1997Ally McBeal (1 Episode) as Dr. Colbert
1997The Shining (1 Episode) as Daniel Edwards (uncredited)
1996Millennium (1 Episode) as County Prosecutor Calvin Smith
1996The Sunchaser as Agent Moreland
1995JAG (1 Episode) as Commander Bradley
1995Bushwhacked as Jon Jordan
1995Awake to Danger as Detective Brickman
1994Beyond Betrayal as Ray Pasquerello
1994ER (1 Episode) as Col. Ken Kilner
1994Chicago Hope (1 Episode) as Unknown
1994One West Waikiki (1 Episode) as Unknown
1994Blind Justice as Spencer Heymen
1993Victim of Love: The Shannon Mohr Story as Dick Britton
1993Diagnosis: Murder (1 Episode) as Sheriff Buck O'Hara
1993The X-Files (1 Episode) as Patrol Captain Van Gelder
1993For Their Own Good as Clark Thompson
1992Lorenzo's Oil as School Psychologist
1992Jennifer Eight as Serato
1992The Gun in Betty Lou's Handbag as Jergens
1989An Unremarkable Life as Michael
1989Sea of Love as Raymond Brown
1981Ghost Story as Churchill
2017On Yoga: The Architecture of Peace ... Producer
2002The Emperor's Club ... Co-Producer