Primarily a stage actor, he is best remembered today for portraying the cool-minded intellectual killer in Alfred Hitchcock's Rope (1948), and the companion of trigger-happy femme fatale Peggy Cummins in the 1950 film noir Gun Crazy.

He first came to fame as the young Welsh mining prodigy who comes alive under the tutelage of Bette Davis in The Corn Is Green (1945), for which he was nominated for the Academy Award for Best Supporting Actor.

[3][Note 2] Dall attended Horace Mann School and briefly enrolled at Columbia University, where he intended to follow in his father's footsteps by studying engineering.

Deciding that acting was his true vocation, he left Columbia and studied at the Theodora Irvine School of Theater and the Pasadena Playhouse.

Dall spent six years acting in various stock companies, notably Clare Tree Major's Children's Theatre.

[25] Dall returned to the stage to play the lead in Norman Krasna's Dear Ruth (1944), under the direction of Moss Hart.

[27] Even before The Corn Is Green was released Warners announced Dall was one of six contractees they intended to build into a star (the others were Lauren Bacall, Dane Clark, Faye Emerson, Robert Hutton and William Prince.

[29] The film rights to Dear Ruth were sold to Paramount who cast William Holden in the part originated by Dall.

Alfred Hitchcock cast Dall in Rope (1948) as one of two killers (the other played by Farley Granger) who match wits with James Stewart.

Dall did "The Wind and the Rain" for Theatre Guild on the Air[41] then returned to Broadway to appear in Daniel Taradash's adaptation of Jean-Paul Sartre's Red Gloves with Charles Boyer, directed by Jed Harris.

[51] Dall did much work in television, appearing in guest roles on such shows as Lights Out ("Pit of the Dead"), The Clock ("A Right Smart Trick"), Studio One in Hollywood ("The Doctor's Wife"[52]), Broadway Television Theatre ("Outward Bound", "The Hasty Heart"), Suspense ("The Invisible Killer", "The Tenth Reunion"), General Electric Theatre ("The Coward of Fort Bennett") and Schlitz Playhouse ("And Practically Strangers").

Film historians William J. Mann and Karen Burroughs Hannsberry have remarked that Dall was gay but claimed in media interviews[17] to have had a brief marriage in the early 1940s.

[59] According to music journalist Phil Milstein, at the time of his death Dall had lapsed into alcoholism and was living with his partner, actor Clement Brace (died 1996).

[60][61] Dall sustained a serious fall while visiting London in October 1970 and died of cardiac arrest, a complication of myocarditis, at his home in Beverly Hills, California, on January 15, 1971, aged 50.