Julianna Luisa Margulies (born June 8, 1966) is an American actress.

After several small television roles, Margulies achieved success in her continuing role as Nurse Carol Hathaway on the NBC medical drama ER (ER (TV series)), for which she won an Emmy Award (Primetime Emmy Award for Outstanding Supporting Actress - Drama Series). After her departure from ER in 2000, Margulies appeared in the 2001 miniseries The Mists of Avalon (The Mists of Avalon (TV miniseries)) and voiced the female iguanadon Neera in the animated film Dinosaur (Dinosaur (film)) (2000). In 2009 she took the lead role in the American legal drama The Good Wife (The Good Wife (TV series)) on CBS, for which she won a Golden Globe (Golden Globe Award for Best Actress - Television Series Drama#2000s) and a Screen Actors Guild Award (Screen Actors Guild Award for Outstanding Performance by a Female Actor in a Drama Series#2000s).