Kay Adams Corleone is a fictional character in Mario Puzo's The Godfather. She was portrayed by Diane Keaton in Francis Ford Coppola's trilogy of films based on the novel.
Born in 1924, Kay is a native of New Hampshire, and the daughter of a Baptist minister. She is the long-term girlfriend and eventual wife of Michael Corleone (Al Pacino), the son of Don Vito Corleone (Marlon Brando), and the future Godfather. Their relationship dates back to their days at Dartmouth College, and the two had sex several times before their marriage. As a non-Italian, she is somewhat of an outsider from the beginning and symbolizes Michael's initial desire to live a more Americanized life, in contrast to the Corleone family's criminal enterprises. Indeed, when she and Michael attend Connie's wedding, they sit at a table separate from the rest of the family. Many of the guests consider Kay's manner to be somewhat freer than they have come to expect from an unmarried woman.
After Michael kills two men who tried to assassinate his father in 1946, he and Kay are separated while he takes refuge in Sicily, where he briefly marries a local young woman, Apollonia (Simonetta Stefanelli). Meanwhile, Kay takes a job as a teacher in her hometown.
Apollonia is accidentally killed by a car bomb intended for Michael. He returns to the United States a year later, when he and Kay reunite and marry after Michael promises to take the family completely legitimate within five years. Due to Michael's marriage to Apollonia occurring entirely in Sicily, Kay is apparently unaware that Michael was a widower when he married her in the USA. Michael becomes the new Don in 1955 after his father's death. They have two children, Anthony and Mary.
When a furious Connie accuses Michael of orchestrating a wave of murders--including that of her husband, Carlo Rizzi--Kay asks Michael if his sister is telling the truth. Michael denies this--but shortly afterward, Kay sees Michael receiving his caporegimes, and sees Clemenza greet him as "Don Michael" (as "Don Corleone" in the film). Kay then realizes Connie was telling the truth after all, and her husband has changed. In the novel, she flees back to New Hampshire with their children, but Tom Hagen persuades her to return. At the end of the novel, Kay converts to Catholicism, going to Mass every day to pray for her husband's soul (just as Mama Corleone had done for Vito).
Kay is still very isolated from the decisions Michael makes as the new Don. At the beginning of The Godfather, Part II (set in 1958-59), Kay, who is pregnant, implores Michael to fulfill his promise of legitimizing the family business. Michael makes a sincere effort to break the family's criminal ties, but his escalating war with rival Hyman Roth (Lee Strasberg) keep him trapped in the criminal underworld and in his personal obsession with revenge. During one of Michael's trips, Kay has an abortion, fearing that another male heir would tie the family to the Mafia forever. While she initially tells Michael that it was a miscarriage, she is increasingly repulsed by the campaign of murder and terror he wages in his war with Roth, and finally decides to leave Michael and take their children with her. However, when she tells Michael that she is leaving him, they get in an argument, and she coldly tells Michael that she did in fact have an abortion. An enraged Michael hits Kay and banishes her from the family; the two are soon divorced.
In the 2004 novel The Godfather Returns, a retcon occurs regarding Kay's termination of her pregnancy. Kay suspects Michael of having their family doctor murdered (as he ostensibly believed that this doctor was responsible for the abortion). Kay confronts Michael and confesses that she had lied; it was, in fact, a miscarriage (due to stress brought on by neglect), and she had lied to Michael in order to hurt him.
In The Godfather, Part III (set in 1979-80), Kay and Michael have not been in contact for several years. Michael has extracted himself from criminal enterprises and has even sold the casinos, and he has been given a knighthood by the Pope, in recognition of his charitable work. After an uneasy reunion, the two reconcile their differences and begin to rekindle their relationship after Michael retires and appoints his nephew Vincent (Andy Garcia) the new Don. In one scene, Michael visits the home of Don Tommasino and has lunch with Kay, during which he apologizes to Kay and asks forgiveness for everything he's done. Michael truthfully tells Kay that he had a whole different destiny planned, and how sorrowful he is that he has lost her. Kay admits that she always loved Michael, and that she always will. Michael reluctantly consents to permit Anthony, to become an opera singer. (Conveniently, he is a tenor. They plan to see his operatic debut, in Palermo.) Just as they begin a new life together, however, their daughter Mary (Sofia Coppola) is killed in an assassination attempt on Michael. Mary's death breaks Michael's spirit, and he withdraws from Kay and from life itself until his lonely death in 1997.