 The second season marked the introduction of Dr. Mark Sloan ( Eric Dane ) and Dr. Callie Torres ( Sara Ramirez ) . They were initially cast as recurring characters , but both were given star billing at the opening of the third season . Ramirez was cast after ABC executives offered her a role in the network show of her choice , Dane had previously auditioned unsuccessfully for a role in the pilot episode . Dr. Addison Montgomery ( Kate Walsh ) also joined the show in season two , after making a guest appearance in season one . In October 2006 , Washington allegedly insulted Knight with a homophobic slur , during an on @-@ set altercation with Dempsey , and ABC terminated Washington 's contract at the end of the third season . Washington also made a guest appearance in season 10 . At the conclusion of the third season , Walsh also departed the show to pursue the Grey 's Anatomy spin @-@ off , Private Practice , but continues to make guest appearances . 
