Joseph Cheshire Cotten, Jr. (May 15, 1905 – February 6, 1994) was an American film, stage and television actor. Cotten achieved prominence on Broadway, starring in the original stage productions of The Philadelphia Story and Sabrina Fair. He first gained worldwide fame in the Orson Welles films Citizen Kane (1941), The Magnificent Ambersons (1942), and Journey into Fear (1943), for which Cotten was also credited with the screenplay. He went on to become one of the leading Hollywood actors of the 1940s, appearing in films such as Shadow of a Doubt (1943), Love Letters (1945), Duel in the Sun (1946), Portrait of Jennie (1948) and The Third Man (1949).

Joseph Cotten was born in 1905 in Petersburg, Virginia, the son of Joseph Cheshire Cotten, Sr., an assistant postmaster and his wife, Sally WillsonCotten. He worked as an advertising agent after studying acting at the Hickman School of Speech and Expression in Washington, D.C. His work as a theatre critic inspired him to become involved in theatre productions, first in Virginia, then in New York City. Cotten made his Broadway debut in 1930.

In 1934 Cotten met and became friends with Orson Welles, a fellow cast member on CBS Radio's The American School of the Air. Cotten had his first starring role in Welles's second production for the Federal Theatre Project — the farce Horse Eats Hat, adapted by Welles and Edwin Denby from Eugène Marin Labiche's play Un Chapeau de Pailled'Italie. The play was presented from September 26 to December 5, 1936, at the Maxine Elliott Theatre, New York.

In 1937 Cotten became an inaugural member of Welles's Mercury Theatre company, starring in Broadway productions of Julius Caesar, The Shoemaker's Holiday and Danton's Death, and in radio dramas presented on The Mercury Theatre on the Air and The Campbell Playhouse.

Cotten made his film debut in the Welles-directed short, Too Much Johnson, a comedy that was intended to complement an aborted 1938 Mercury stage production of William Gillette's 1890 play. The film was never screened in public; it was reported in 2013 that a print had been discovered in Prodenone, Italy.

Cotten returned to Broadway in 1939, creating the role of C. K. Dexter Haven opposite Katharine Hepburn's Tracy Lord in the original production of Philip Barry's The Philadelphia Story. The play ran for a year at the Shubert Theatre, and in the months before its extensive national tour a film version was to be made by MGM. Cotten went to Hollywood, but discovered there that his stage success in The Philadelphia Story translated to, in the words of his agent Leland Hayward, "spending a solid year creating the Cary Grant role." Hayward suggested that they call Cotten's good pal, Orson Welles. "He's been making big waves out here," Hayward said. "Maybe nobody in Hollywood ever heard of the Shubert Theatre in New York, but everybody certainly knows about the Mercury Theatre in New York."