Sherry Lea Stringfield (born June 24, 1967) is an American actress. She is best known for playing the role of Dr. Susan Lewis on the NBC medical drama "ER", a role for which she received three Emmy Award nominations. Stringfield was a member of "ER's" original cast, but she quit the show during its third season, despite being contractually tied to appear in five. She returned to the role in 2001, and quit once again in 2005. She is also known for her regular roles on "NYPD Blue" and "Guiding Light".