Joan de Beauvoir de Havilland (October 22, 1917 – December 15, 2013), known professionally as Joan Fontaine, was a British-American actress best known for her starring roles in Hollywood films. Fontaine appeared in more than 45 feature films in a career that spanned five decades. She was the younger sister of actress Olivia de Havilland.

Born in Tokyo to British parents, Fontaine moved to California before she was two years old. She traveled there along with her mother, Lilian Fontaine, and sister, the actress Olivia de Havilland, following her parents' divorce. She was anaemic as a child, and her childhood was consequently marred by poor health, but she had improved by her teen years. After living in Japan and attending school there for a short while, she began her stage career in 1935, signing a film contract with RKO Pictures. Fontaine received her first major role in The Man Who Found Himself (1937); however, she failed to make a significant impression and her contract was not renewed.

Her career prospects improved greatly after her starring role in the Alfred Hitchcock-directed Rebecca (1940), for which she received the first of what would be three nominations for the Academy Award for Best Actress; the following year, she won for her role in Suspicion (1941). A third Oscar nomination came with the film The Constant Nymph. She appeared mostly in drama films through the 1940s"including Letter from an Unknown Woman, which is now considered a classic. In the next decade, her career began to decline and she moved into stage and television roles. She appeared in fewer films into the 1960s, her final feature film being The Witches (1966).

For most of her middle to later life, Fontaine was active in radio, television, and the stage. She released an autobiography, No Bed of Roses, in 1978; she continued to act until her last performance in 1994. Fontaine lived in Carmel Highlands, California, where she owned a home, Villa Fontana. She died there of natural causes at the age of 96 in 2013. Having won an Academy Award for her role in Suspicion, Fontaine is the only actor to have won an Academy Award for acting in a Hitchcock film. Furthermore, she and her sister remain the only siblings to have won major acting Academy Awards.

Married four times, she had one child by birth and one child by adoption, from whom she was later estranged. Her relationship with her sister was long known to be acrimonious, and included long periods of estrangement, especially in later life.