Isobel Katherine "Izzie" Stevens, M.D. is a fictional character from the medical drama television series "Grey's Anatomy", which airs on the American Broadcasting Company (ABC) in the United States.
 The character was created by series producer Shonda Rhimes, and was portrayed by actress Katherine Heigl from 2005 to 2010.
 Introduced as a surgical intern at the fictional Seattle Grace Hospital, Izzie worked her way up to resident level, while her relationships with her colleagues Meredith Grey (Ellen Pompeo), Cristina Yang (Sandra Oh), George O'Malley (T.R. Knight) and Alex Karev (Justin Chambers) formed a focal point of the series.
Owen Hunt, M.D. is a fictional character from the medical drama television series "Grey's Anatomy", which airs on the American Broadcasting Company (ABC) in the United States.
 The character was created by series' producer Shonda Rhimes, and is portrayed by actor Kevin McKidd.
 He was introduced in season five as a U.S. Army trauma surgeon who served in war-torn Iraq, and subsequently joins the fictional Seattle Grace Hospital to teach medicine as a surgical attending, head of trauma surgery, and eventual chief of surgery, sometimes with unorthodox methods.
 Originally contracted to appear for a multi-episode story arc, he was upgraded to a series' regular at the conclusion of his first appearance.
Meredith Grey, M.D. is a fictional character from the medical drama television series "Grey's Anatomy", which airs on the American Broadcasting Company (ABC) in the United States.
 The character was created by series' producer Shonda Rhimes, and is portrayed by actress Ellen Pompeo.
 Meredith is the series' protagonist, and was introduced as a surgical intern at the fictional Seattle Grace Hospital (later Seattle Grace-Mercy West, and afterwards Grey Sloan Memorial), eventually obtaining the position of a resident, and later the position of an attending, and in 2015, attaining the Chief of General Surgery position.
 As the daughter of world-renowned surgeon Ellis Grey, Meredith struggles with the everyday life of being in a competitive profession, maintaining the relationship with her one-night stand and eventual husband Derek Shepherd (deceased), her motherhood, and her friendships with her colleagues.
Boone Carlyle is a fictional character who was played by Ian Somerhalder on the ABC drama television series "Lost", which chronicles the lives of the survivors of a plane crash in the south Pacific.
 Boone is introduced in the pilot episode as the stepbrother of fellow crash survivor Shannon Rutherford.
 He tries to contribute as much as he can to the safety of the castaways and eventually becomes John Locke's protégé.
Lost is an American drama television series that originally aired on the American Broadcasting Company (ABC) from September 22, 2004, to May 23, 2010, over six seasons, comprising a total of 121 episodes.
 The show contains elements of supernatural and science fiction, and follows the survivors of a commercial jet airliner crash, flying between Sydney and Los Angeles, California, on a mysterious tropical island somewhere in the South Pacific Ocean.
 The story is told in a heavily serialized manner.
 Episodes typically feature a primary storyline set on the island, augmented by flashback or flashforward sequences which provide additional insight into the involved character(s).
Center Stage is an American television anthology series that aired in 1954 on the American Broadcasting Company as a summer replacement for "The Motorola Television Hour".
 It aired on the American Broadcasting Company (ABC) on alternate weeks from June 1, 1954 to September 21, 1954, swapping airings with the "U.S. Steel Hour".
 The series was produced by Herbert Brodkin.
 There were nine episodes, one of which was written by Rod Serling.
 Among its stars were Walter Matthau, Charles Coburn, Lee Marvin, and Vivian Blaine.
Shannon Rutherford is a fictional character played by Maggie Grace on the ABC drama television series "Lost", which chronicled the lives of the survivors of a plane crash in the South Pacific.
 Shannon was introduced in the pilot episode as the stepsister of fellow crash survivor Boone Carlyle (Ian Somerhalder).
 She was a series regular until her funeral in "What Kate Did".
 For most of her time on the Island, she was unhelpful and spent much of her time sunbathing.
 She formed a relationship with another survivor from the plane crash, Sayid Jarrah (Naveen Andrews).
 Shannon was accidentally shot by Ana Lucia Cortez who mistakes her for an Other.
"Lost" is an American television drama that debuted on the American Broadcasting Company (ABC) on September 22, 2004.
 The series aired for six seasons, and follows the survivors of the crash of the fictional Oceanic Flight 815 on a mysterious tropical island somewhere in the South Pacific.
 Although a large cast made "Lost" more expensive to produce, the writers benefited from added flexibility in story decisions.
 According to series executive producer Bryan Burk, "You can have more interactions between characters and create more diverse characters, more back stories, more love triangles." The initial season had 14 regular speaking roles that received star billing.
 Matthew Fox played the protagonist, a troubled surgeon named Jack Shephard.
 Evangeline Lilly portrayed a fugitive Kate Austen.
 Jorge Garcia played Hugo "Hurley" Reyes, an unlucky lottery winner.
 Josh Holloway played a con man, James "Sawyer" Ford.
 Ian Somerhalder played Boone Carlyle, chief operating officer of his mother's wedding business.
 Maggie Grace played his stepsister Shannon Rutherford, a former dance teacher.
 Harold Perrineau portrayed construction worker and aspiring artist Michael Dawson, while Malcolm David Kelley played his young son, Walt Lloyd.
 Terry O'Quinn played the mysterious John Locke.
 Naveen Andrews portrayed former Iraqi Republican Guard Sayid Jarrah.
 Emilie de Ravin played a young Australian mother-to-be, Claire Littleton.
 Yunjin Kim played Sun-Hwa Kwon, the daughter of a powerful Korean businessman and mobster, with Daniel Dae Kim as her husband and father's enforcer Jin-Soo Kwon.
 Dominic Monaghan played English ex-rock star drug addict Charlie Pace.
George O'Malley is a fictional character from the medical drama television series "Grey's Anatomy", which airs on the American Broadcasting Company (ABC) in the United States.
 The character was created by series producer Shonda Rhimes, and was portrayed by actor T. R. Knight from 2005 to 2009.
 Introduced as a surgical intern at the fictional Seattle Grace Hospital, O'Malley worked his way up to resident level, while his relationships with his colleagues Meredith Grey (Ellen Pompeo), Cristina Yang (Sandra Oh), Izzie Stevens (Katherine Heigl) and Alex Karev (Justin Chambers) formed a focal point of the series.
 O'Malley married Callie Torres (Sara Ramirez) whom he later separated with to pursue a relationship with Izzie Stevens.
 O'Malley also had entertained a romantic interest with Meredith Grey and Olivia Harper (Sarah Utterback).
Cristina Yang, M.D., Ph.D., is a fictional character from the medical drama television series "Grey's Anatomy", which has aired for over 12 years on the American Broadcasting Company (ABC) in the United States.
 The character was created by series producer Shonda Rhimes, and is portrayed by actress Sandra Oh.
 Introduced as a surgical intern at the fictional Seattle Grace Hospital, Yang worked her way up to resident level, eventually becoming a cardiothoracic surgical fellow, while her relationships with colleagues Meredith Grey (Ellen Pompeo), George O'Malley (T. R. Knight), Izzie Stevens (Katherine Heigl), and Alex Karev (Justin Chambers) formed a focal point of the series.
 Yang earlier in the series got engaged to Preston Burke (Isaiah Washington), in the past had a relationship with renowned surgeon and mentor Colin Marlow, and wed but later divorced Owen Hunt (Kevin McKidd).

Question: Which American drama television series that originally aired on the American Broadcasting Company (ABC),  comprising a total of 121 episodes, included a fictional character who was played by Ian Somerhalder? 
Answer: Lost