American writer and director of plays and films, best known for collaborations with his wife, the actress-writer Ruth Gordon (Gordon, Ruth).

Kanin left high school to help support his family during the first years of the Great Depression. He worked as a musician and later as a comedian, and he eventually attended the American Academy of Dramatic Arts during the years 1932–33. Upon completing his studies, he acted briefly on Broadway and then assisted Broadway director George Abbott, from whom he learned the basics of stage direction. These experiences sparked Kanin's interest in a directing career.

In 1937 Kanin joined film producer Samuel Goldwyn (Goldwyn, Samuel)'s staff, but he left after a year because he received no directing assignments. He signed with RKO (RKO Radio Pictures, Inc.) studios in 1938 and was immediately assigned to direct A Man to Remember (1938). The following year, he enjoyed his first directorial success with The Great Man Votes (1939) after having personally talked actor John Barrymore (Barrymore, John) into taking the lead role. Kanin's best films at RKO include My Favorite Wife (1940), with Cary Grant (Grant, Cary), and Tom, Dick, and Harry (1941), with Ginger Rogers (Rogers, Ginger).

Drafted during World War II, Kanin made documentary films for the War Information and Emergency Manpower offices. One of them, The True Glory (1945), codirected by Carol Reed (Reed, Sir Carol), won an Academy Award for best documentary. After the war, he directed his play Born Yesterday on Broadway; in 1950 it was made into a film by director George Cukor (Cukor, George). Kanin also cowrote several screenplays with Gordon (Gordon, Ruth), including A Double Life (1947), Adam's Rib (1949), and Pat and Mike (1952). Throughout their productive careers, Kanin and Gordon wrote scripts strictly on a freelance basis and were never under contract to any Hollywood studio.

Kanin also wrote novels, including Blow Up a Storm (1959), A Thousand Summers (1973), and Moviola (1979); a collection of short stories entitled Cast of Characters (1969); and nonfiction such as Tracy and Hepburn: An Intimate Memoir (1971), Hollywood (1974), and Together Again! The Stories of the Great Hollywood Teams (1981). He was the sole writer for such screenplays as It Should Happen to You (1954) and The Rat Race (1960; based on his play and novel of the same name). He also wrote several scripts for television, including Hardhat and Legs (1980), which was his final collaboration with Gordon.