Carrie Anne Mathison, played by actress Claire Danes, is a fictional character and the protagonist of the American television drama/thriller series Homeland on Showtime, created by Alex Gansa and Howard Gordon. Carrie is a CIA officer who, while on assignment in Iraq, learned from a CIA asset that an American prisoner of war had been turned by al-Qaeda. After a U.S. Marine sergeant named Nicholas Brody is rescued from captivity, Carrie believes that he is the POW described to her. Carrie's investigation of Brody is complicated by her bipolar disorder and results in an obsession with her suspect.

For her performance, Danes received several major acting awards, including the Primetime Emmy Award for Outstanding Lead Actress in a Drama Series, the Golden Globe Award for Best Actress – Television Series Drama, the Screen Actors Guild Award for Outstanding Performance by a Female Actor in a Drama Series, the Satellite Award for Best Actress – Television Series Drama, and the TCA Award for Individual Achievement in Drama. She is the second actress to win all the five main TV acting awards for her performance in the Lead Drama Actress categories.

Carrie Anne Mathison was an Arabic language student at Princeton University, where she was recruited into the CIA by veteran officer Saul Berenson (Mandy Patinkin). Carrie developed a close working relationship with Saul, and is implied to have had a sexual relationship with CTC Director David Estes (David Harewood), her future boss, which contributed to the breakup of his marriage. In college, Carrie was diagnosed with bipolar disorder, for which she secretly began taking clozapine supplied by her older sister, Maggie (Amy Hargreaves), a psychiatrist.

As a field operative in Iraq, Carrie infiltrated a prison to meet with an imprisoned CIA asset named Hasan Ibrahim, who claimed that he had information regarding an imminent terrorist attack in the United States. Moments before his execution, Hasan told Carrie that an American prisoner of war was turned by al-Qaeda figure Abu Nazir (Navid Negahban). Carrie's unauthorized dealings with Hasan led to an international incident, causing Estes to have her reassigned to the CIA's Counterterrorism Center in Langley, Virginia.

Ten months after her reassignment, Carrie attends an emergency staff meeting and learns that Nicholas Brody (Damian Lewis), a U.S. Marine sergeant, has been rescued after eight years in terrorist captivity. Carrie tells Saul about Hasan's claims, and expresses concern that Brody is the POW he was describing. With the CIA having no cause to investigate Brody, Carrie conducts her own unauthorized surveillance using a one-month FISA warrant delivered by Saul. Initially, Carrie finds no evidence of Brody's involvement with terrorism.

When her FISA warrant expires, Carrie takes to making personal contact with Brody instead. She bumps into Brody at a veterans' support group, where they strike up a conversation and immediately bond over their mutual experiences in the Middle East. Brody asks Carrie to have a drink with him one night, culminating in a drunken sexual encounter in Carrie's car. The next day, he is brought to Langley for a polygraph over the apparent suicide of Afsal Hamid (Waleed Zuaiter), a detained terrorist with whom Brody had a violent confrontation. Carrie, suspicious of Brody's replies, tells the interviewer to ask if he has ever been unfaithful to his wife. Brody says "no", beating the polygraph.

Afterwards, Carrie and Brody drive to her family's secluded cabin to spend the weekend together. However, after Carrie mentions his preference for Yorkshire Gold tea, which she learnt about through surveillance, Brody realizes she has been spying on him. She forces him to admit to his conversion to Islam, his meeting with and personal affection for Nazir, and his murder of a fellow POW named Tom Walker under duress. As Brody leaves, Saul contacts Carrie and informs her that Walker (Chris Chalk) is alive and was the POW who was turned. Carrie tries to apologize to Brody, but he rebuffs her and goes back to his family.

The investigation into Walker leads Carrie and Saul to Mansour al-Zahrani (Ramsey Faragallah), a Saudi diplomat who acts as Nazir's intermediary. Carrie blackmails al-Zahrani into arranging a meeting with Walker at Farragut Square. However, the meet ends in disaster when Walker detonates a briefcase bomb carried by a double, killing al-Zahrani and three bystanders. Carrie is injured in the explosion, leading to a severe manic episode that causes her to be hospitalized. Upon learning of her affair with Brody, Estes — already under pressure by Vice President William Walden (Jamey Sheridan) to find a scapegoat for the bombing — dismisses Carrie from the CIA.