Gaines was born in Indian Territory and grew up in Texas, learning "to handle the ax, the plough, and the lariat".^[1] He enrolled at Texas Christian University when he was 16 and studied drama there. While a student there he acted in productions of little theaters in Dallas and Fort Worth.^[1]

He worked at a variety of jobs in the United States and in France before winning a scholarship to study at the American Laboratory Theatre.^[1]

Gaines appeared in five Broadway productions between 1929 and 1942. He served as Raymond Massey's replacement as Abraham Lincoln in the original production of Robert E. Sherwood's Abe Lincoln in Illinois (1938–1939).^[2]

In Hollywood, Gaines frequently played professional or officious types in supporting roles.^[3] He was often seen in authoritarian roles as a lawyer, doctor, supervisor or father. Gaines made his film debut as Patrick Henry in the historical drama The Howards of Virginia with Cary Grant. One of his best-known roles was as Jean Arthur's stuffy suitor Charles J. Pendergast in The More the Merrier (1943), directed by George Stevens. He also appeared as the insurance company boss of Fred MacMurray and Edward G. Robinson in the film noir classic Double Indemnity (1944). In Cecil B. DeMille's Unconquered (1947), Gaines portrayed the historical role of George Washington. He worked frequently on television during the 1950s. Between 1958 and 1961, he had a recurring role as a judge in 14 episodes of Perry Mason.

On September 30, 1936, Gaines married actress Brenda Marshall; the couple divorced in 1940.^[4] They had one daughter, Virginia, who later grew up with Marshall and her second husband William Holden after Holden subsequently adopted Virginia Gaines when the couple married in 1941. Gaines retired from Hollywood business in 1962 after a guest appearance on Alfred Hitchcock Presents, and he died in North Hollywood, Los Angeles, on July 20, 1975, three days before his 71st birthday.

• Richard Gaines at IMDb