About
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...
Known for
Ally McBealSeries • 1997
NCISSeries • 2003
Grey's AnatomySeries • 2005
The MentalistSeries • 2008
Criminal MindsSeries • 2005
CSI: MiamiSeries • 2002
NCIS: Los AngelesSeries • 2009
The X-FilesSeries • 1993
JAGSeries • 1995
S.W.A.T.Series • 2017
24Series • 2001
Prison BreakSeries • 2005
Diagnosis: MurderSeries • 1993
TrackerSeries • 2024
FringeSeries • 2008
The West WingSeries • 1999
Sons of AnarchySeries • 2008
War of the WorldsMovie • 2025
ERSeries • 1994
This Is UsSeries • 2016
Without a TraceSeries • 2002
Rizzoli & IslesSeries • 2010
Ghost WhispererSeries • 2005
Boston LegalSeries • 2004