<Li> Jessica Capshaw as Dr. Arizona Robbins </Li> <Li> Kim Raver as Dr. Teddy Altman </Li> <Li> Patrick Dempsey as Dr. Derek Shepard </Li> <P> The season was produced by Touchstone Television ABC Studios, The Mark Gordon Company, Shondaland and was distributed by Buena Vista International, Inc...The executive producers were creator Shonda Rhimes, Betsy Beers, Mark Gordon, Krista Vernoff, Rob Corn, Mark Wilding, Joan Rater and James D. Parriott . The regular directors were Shonda Rhimes, Krista Vernoff, Stacy McKee, William Harper, Debora Cahn, Allan Heinberg and Peter Nowalk . At the conclusion of season five, T.R. Knight was released from his contract, following a disagreement with Rhimes . When asked to make a' flashback' appearance in season six, Knight declined . Heigl's appearances in the season were sporadic, seeing Stevens depart and return twice . Although she was scheduled to appear in the final five episodes of the season, Heigl requested that she be released from her contract 18 months early, and made her final appearance on January 21, 2010 . Heigl explained that she wanted to spend more time with her family, and did not think it would be respectful to Grey's Anatomy viewers to have Izzie return and depart yet again . The season's two - hour opener showed the doctors of Seattle Grace Hospital, grieving the loss of their deceased friend, O'Malley . The special's writer, Vernoff, commented: "It's heartbreaking . I fell in love with George, like many of you did, in season one ." </P>

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