High Quality Content by WIKIPEDIA articles! The sixth season of the American television medical drama Grey`s Anatomy, commenced airing on the American Broadcasting Company (ABC) in the United States on September 24, 2009, and concluded on May 20, 2010. The season was produced by ABC Studios, in association with Shondaland Production Company and The Mark Gordon Company; the showrunner being Shonda Rhimes. Actors Ellen Pompeo, Sandra Oh, Katherine Heigl, and Justin Chambers reprised their roles as surgical residents Meredith Grey, Cristina Yang, Izzie Stevens, and Alex Karev, respectively. Heigl was released from her contract in the middle of the season, while T.R. Knight did not appear as George O`Malley, because Knight was released from his contract at the conclusion of season five. Main cast members Patrick Dempsey, Chandra Wilson, James Pickens, Jr., Sara Ramirez, Eric Dane, Chyler Leigh, and Kevin McKidd also returned, while previous recurring star Jessica Capshaw was promoted to a series regular, and Kim Raver was given star billing after the commencement of the season.