American actor best known for his performances in several film classics of the 1940s, particularly those directed by Orson Welles (Welles, Orson).

After a brief stint as a part-time drama critic for the Miami Herald, Cotten embarked on an acting career in 1930. He found some success on Broadway, including a leading role opposite Katharine Hepburn (Hepburn, Katharine) in The Philadelphia Story (1939). In 1937 he began his long association with Welles as a member of the Federal Theatre Project and joined Welles's and John Houseman's Mercury Theatre ensemble of radio actors in 1938.

The Mercury players were featured in most of the leading roles in Welles's first film, Citizen Kane (1941), frequently cited by critics as the greatest movie ever made. Cotten was outstanding in his screen debut as drama critic Jed Leland, and he delivered another fine performance in Welles's next film, The Magnificent Ambersons (1942), also regarded as a masterpiece. Cotten again costarred with the Mercury ensemble in Journey into Fear (1942), for which he collaborated with Welles on the screenplay. The 1940s proved to be Cotten's most successful years; virtually every film he appeared in during the decade is regarded as a classic. He delivered his three most heralded performances in Alfred Hitchcock's Shadow of a Doubt (1943), William Dieterle's Portrait of Jennie (1948), and Carol Reed's The Third Man (1949). He was also memorable in I'll Be Seeing You (1944), Gaslight (1944), Since You Went Away (1944), Love Letters (1945), Duel in the Sun (1946), and The Farmer's Daughter (1947). In these films, Cotten established a rather complex screen persona—that of a weak man with a strong facade: ingratiating but cynical, decent but ineffectual, charming but largely impotent.

Although he never again attained such prominence, Cotten appeared in more than 75 films during the next three decades before his retirement in 1981. He was regarded as a dependable character actor and appeared in such disparate fare as Niagara (1953), Welles's Touch of Evil (1958), the science-fiction story From the Earth to the Moon (1958), and the gothic shocker Hush…Hush, Sweet Charlotte (1964), and his performance in the critically reviled Heaven's Gate (1980) was singled out for praise. He also was a guest star on several television shows during the 1960s and '70s, and he toured extensively in stage productions with his wife, actress Patricia Medina.