Carol Hathaway is a fictional character from the NBC medical drama series ER, portrayed by actress Julianna Margulies.

In season 3, Carol decides to attend pre-med classes at a local community college and eventually takes the MCAT exam.

Episodes later, when Carol's application to adopt an abandoned child is denied due to her attempt, she tells Doug that she feels defective, and that she has worked hard in therapy since that day.

After physician assistant Jeanie Boulet's HIV status is revealed to the staff, Carol privately tells her about her suicide attempt and explains that she knows what it's like to come back to work and have everyone treat you differently.

After caring for the patient, Shep comments - unaware of Carol's history - that anyone who takes a bunch of pills just wants attention and does not really mean it.

I even tried to go to med school, but it just wasn’t for me.” Also in the season four episode, “Of Past Regret and Future Fear”, Carol tells Doug that her father suffered from depression.

Their conversation hints that his depression may have been a factor in his death, with Carol's mother believing “it was an accident.” Shortly after her character is introduced on the show, she is rushed into the hospital after an overdose of barbiturates in a suicide attempt.

Carol is close friends with both Dr. Lewis and Dr. Greene, and the two order aggressive medical care, which results in her miraculously surviving after being comatose for several hours.

Although she later denies it, the staff suspects that her suicide attempt was brought about by her failed romance with Doug Ross, a womanizing pediatrician also working in the ER.

In an attempt to move on from her fractured relationship with Doug, Carol plans to marry orthopedic surgeon John "Tag" Taglieri (Rick Rossovich).

The relationship is tumultuous from the start, since Carol cannot commit fully to Tag, and against his wishes, she tries unsuccessfully to adopt a Russian child suffering from AIDS who was abandoned in the ER.

In season one, episode nine, after giving advice to a patient to be more honest, Carol tells Tag that she cheated on him with Doug before her suicide attempt and recently kissed him.

While she seems to acknowledge that she and Tag were not a strong relationship, Carol is still hurt, telling Doug in the final episode of season one, "I just want to be happy and I'm so afraid I never will be."

As the seasons progress, the house slowly transforms into a vibrant living space, mirroring Carol's work to rebuild her life.

Despite Carol's attempts to get him professional help, he refuses, so she ends their relationship, telling him that she has finally gotten her life together and can not be with him if he is not seeking therapy for his problems.

Carol opens up a free clinic in the ER, backed financially by colleague Dr. John Carter's wealthy grandmother.

Doug, the once-womanizing pediatrician, hits rock bottom, leading a life of celibacy after one of his one-night stands dies from a cocaine overdose.

Doug's constant run-ins with authority begin to jeopardize not only his job, but also his relationship with Carol, who — despite her devotion — finds it increasingly difficult to support his reckless decisions regarding patient care.

Using a PCA machine from Carol's clinic, Doug authorizes the mother, Joi, to administer enough pain medication to stop his heart.

She is kicked in the stomach by a child, faced with the need to care for a woman who has an infection that is dangerous to pregnant women, and accidentally exposed to an x-ray.

She is assisted by then-OB nurse Abby Lockhart, as well as by her long-time friend and colleague, Dr. Mark Greene, as her birthing coach.

When Doug learns of his twin daughters' birth via a telephone call from Carol, he again invites them to come and live with him in Seattle.

Dr. Luka Kovač, a new Attending from Croatia who lost his wife and children in the Croatian War of Independence, often helps Carol take care of the twins.

Eight years after her departure, in the Season 14 episode, "Status Quo", Jeanie Boulet mentions Doug and Carol when she returns to the ER after her ex-husband's death and learns of brain lesions due to AIDS progression in her son.

In 2014, The Atlantic ranked Carol Hathaway at the top of its list of the 45 most memorable ER characters, referring to her as the most beloved hero on the show.

[19][20][21] Entertainment Weekly placed Hathaway in its list of the "30 Great TV Doctors and Nurses.”[22] Parade named her one of the best fictional nurses on television.

[27] In 2016, a podcast episode of Advanced TV Herstory noted the uniqueness of ER in having a character “attempt suicide and recover, only to be put back into the same stressful workplace.”[28] The podcast, hosted by Cynthia Bemis Abrams, observed that the character of Carol Hathaway was often more knowledgeable and skilled than the medical students, and that her high expectations for herself made for a worthwhile story arc.

[31][32] In 2022, Entertainment Weekly ranked them 33rd on its list of the 100 Best TV Romances of All Time, with Carol noted by the magazine as a nurse who doesn't suffer fools gladly.

[34] In an episode of Leverage: Redemption that guest-starred fellow ER star Noah Wyle, Carol Hathaway is the alias used by the character, Sophie, when she is acting as a nurse.

[36] During an interview on Late Night with Seth Meyers in 2021, actress Amy Poehler shared her desire to meet with Julianna Margulies to ask a list of questions she had about Carol Hathaway.