Carol Hathaway was played by Julianna Margulies. Her first appearance was in the pilot movie & her character was originally supposed to die. However she was written into the show and stayed until the end of season 6 when she went to Seattle to be with Doug Ross. Her last appearance was in the 19th episode of the last season, season 15.

Carol is a registered nurse & was the nurse manager in the ER. She is a fierce leader and is always seeking recognition for her nurses. Carol did go to classes and wanted to go to medical school to become a doctor but decided to stay a nurse. She later got funding from Carter's grandmother to open up a ER clinic to care for people for free. She was later forced to step down along with stepping down from being the nurse manager.

Carol had a lot of lost loves including Tag (who she was engaged to & was left on the altar), Shep (who moves in with her in her run down house but she breaks up with him when he refuses to get help for his anger issues), & Doug (they have a on and off again relationship but eventually she moves to Seattle to be with him. Carol has their twin daughters, Kate & Tess, on Thanksgiving day with Mark Greene as her birth coach. It is after she has the twins that Doug invites her out to Seattle and she takes a chance after a series of events in the ER move Carol.

Carol has gone through a lot of trials herself. She attempted suicide, was put on suspension, was also held hostage at gunpoint during a robbery, and had a scandal involving Doug & a terminally ill boy.

In Season 15, Carol & Doug are married and practicing in Seattle where Carol is now a transplant coordinator.