Erica Hahn, M.D. is a fictional character from the American Broadcasting Company medical drama television series Grey's Anatomy, portrayed by actress Brooke Smith. Hahn was a recurring character through the show's second and third seasons, and joined the main cast in the fourth season. Prior to assuming the role, Smith observed heart surgery being performed, and admitted to finding stressful the pressure of continually portraying a medical professional realistically. The character is presented as highly professional, to the point of being a "workaholic". She is notably hard on Resident Cristina Yang, admitting that Cristina reminds her of herself as a student. Despite her intentions to keep away from relationships, she becomes romantically involved with orthopedic surgeon Callie Torres. The storyline was praised for its realistic portrayal of a developing lesbian relationship, although consultants from the Gay & Lesbian Alliance Against Defamation expressed some concerns over what they deemed the somewhat exploitative talk of a threesome between Hahn, Torres and Mark Sloan.