Luther Adler (May 4, 1903 – December 8, 1984) was an American actor best known for his work in theater, but who also worked in film and television. He also directed plays on Broadway.

Born Lutha Adler in New York, New York, Adler was one of six children born to Russian Jewish actors Sara and Jacob P. Adler. His siblings also worked in theater, with his sister Stella Adler achieving fame as an actress and drama teacher.

Adler made his first acting appearance on Broadway in 1921 and appeared in several productions before joining The Group Theatre in 1931. He played opposite Katharine Cornell in Alien Corn (1933), his sister Stella in Gold Eagle Guy (1934), Awake and Sing! and Paradise Lost (both 1935), and Frances Farmer in Golden Boy (1937). By the early 1940s he was also directing but his first production They Should Have Stood in Bed closed after only eleven performances in 1942. His next directorial venture A Flag is Born ran for 120 performances in 1946 and featured newcomer Marlon Brando in one of the major roles.

From 1937 Adler also appeared in films, although they were never his highest priority. Among his credits are M , Voyage of the Damned (1976) and Absence of Malice (1981). He also acted frequently on television in such television series as General Electric Theater, Kraft Television Theater Robert Montgomery Presents, The Twilight Zone, The Untouchables, Ben Casey, 77 Sunset Strip, Mission: Impossible, Hawaii Five-O and The Streets of San Francisco.

Adler was married to the actress Sylvia Sidney from 1938 until 1947.

He died in Kutztown, Pennsylvania and was buried in Mount Carmel Cemetery, New York.