Mapother at the South by Southwest festival in March 2007.
|Born||William Reibert Mapother, Jr.
April 17, 1965
Louisville, Kentucky, U.S.
Personal life 
Mapother was born in Louisville, Kentucky, the son of Louisa (Riehm) and William Reibert Mapother, Sr. He is of English, Irish, and predominantly German ancestry. He is a first cousin of actor Tom Cruise (whose given name is Thomas Cruise Mapother IV). Mapother has appeared in five movies starring Cruise. He had a cameo role in Minority Report, Vanilla Sky, and supporting roles in Mission: Impossible II, Born on the Fourth of July, and Magnolia. Mapother has two sisters, Katherine and Amy (an occasional actress, born February 17, 1974), both born in Louisville, Kentucky. His father was an attorney, bankruptcy consultant and judge in Louisville, between 1967 and 1970; William Sr., died on June 22, 2006, after fighting lung cancer and pulmonary fibrosis.
Mapother has become widely known as a character actor, who sometimes plays scary or otherwise dark characters. Despite playing a pivotal role in Todd Field's In the Bedroom, Mapother is perhaps more widely known as Ethan Rom in the TV show Lost. The character was killed off early in the first season, but since then has appeared in seven episodes mainly through flashbacks, once due to time travel and another in an alternate timeline. In all, he appeared in eleven episodes of Lost.
Mapother has also had considerable roles in a series of independent films, such as The Lather Effect, Moola, Hurt, and Another Earth. Mapother starred in The Burrowers as a former Indian fighter who joins a posse to help find missing white settlers, only to discover that the hunters have become the hunted.
In September 2007, he was elected to a three-year term on the National Board of Directors for the Screen Actors Guild.
- American Horror Story (TV, 1 episode, 2012) .... Misogynist Driver
- Justified (TV, 2 episodes, 2012) .... Delroy Baker
- The Mentalist (TV, 1 episode, 2011) .... Richard Haibach
- Edwin Boyd: Citizen Gangster (2011) .... Detective Rhys
- Warrior (2011) .... David Milligan
- A Warrior's Heart (2010)
- Another Earth (2010) .... John Burroughs
- Hurt (2008) .... Darryl Coltrane
- Prison Break (TV, 2 episodes, 2009) .... FBI Agent Chris Franco
- Lost (TV, 11 episodes, 2004–2010) .... Ethan Rom
- Criminal Minds (TV, 1 episode, 2008) .... Ian Corbin
- The Burrowers (Film, 2008) .... Will Parcher
- Lost: Missing Pieces (TV, 1 episode, 2008) .... Ethan Rom
- Skip Tracer (TV, 2008) .... Henry Hargrove Jr.
- WordGirl (TV animation, 2007) ... Guy Rich (voice)
- Viva Laughlin (TV, 1 episode, 2007) .... Sweet Lenny Collins
- K-Ville (TV, 1 episode, 2007) .... Gordon Wix
- Moving McAllister (2007) .... Bob
- Moola (2007) .... Steve
- Robot Chicken (TV, 2 episodes, 2006) .... Alien Bully / Leprechaun #2
- World Trade Center (2006) .... Jason Thomas
- The Lather Effect (2006) .... Jack
- Ask The Dust (2006) .... Bill
- Crossing Jordan (TV, 1 episode, 2005) .... Henry Bishop
- Threshold (TV, 2 episodes, 2005) .... Gunneson
- Chloe (2005) .... Doctor
- The Zodiac (2005) .... Dale Coverling
- Lords of Dogtown (2005) .... Donnie
- The Inside (TV, 1 episode, 2005) .... Ronald Ewing
- The Grudge (2004) .... Matthew Williams
- NCIS (TV, 1 episode, 2004) .... Kyle Grayson
- CSI: Miami (TV, 1 episode, 2004) .... Pete Keller
- Suspect Zero (2004) .... Bill Grieves
- Line of Fire (TV, 2 episodes, 2004) .... Larry
- The Kiss (2003) .... Peter
- Touched by an Angel (TV, 2 episodes, 2003) .... Eddie
- Law & Order: Special Victims Unit (TV, 1 episode, 2003) .... Luke Edmunds
- The Pennsylvania Miners' Story (TV, 2002) .... John 'Flathead' Phillippi
- CSI: Crime Scene Investigation (TV, 1 episode, 2002) .... Douglas Sampson
- Self Storage (2002) .... Graham
- Minority Report (2002) .... Hotel Clerk
- Swordfish (2001) .... Gabriel's Crew
- In the Bedroom (2001) .... Richard Strout
- Almost Famous (Scenes Deleted, 2000) .... Bartender
- Mission: Impossible II (2000) .... Wallis
- Magnolia (1999) .... WDKK Show Director's Assistant
- The Unknown Cyclist (1998) .... By-Stander
- Trickle (1998) .... Josh Riddell
- Without Limits (1998) .... Bob Peters
- Born on the Fourth of July (1989) .... Platoon Member – Vietnam
- Official blog
- Official website
- William Mapother at the Internet Movie Database
- William Mapother interview with the Horror Asylum