- Farley Granger as Guy Haines
- Ruth Roman as Anne Morton
- Robert Walker as Bruno Antony
- Leo G. Carroll as Senator Morton
- Patricia Hitchcock as Barbara Morton
- Kasey Rogers as Miriam Joyce Haines
- Marion Lorne as Mrs. Antony
- Jonathan Hale as Mr. Antony
- Howard St. John as Police Capt. Turley
- John Brown as Professor Collins
- Norma Varden as Mrs. Cunningham
- Robert Gist as Detective Hennessey
Alfred Hitchcock's cameo appearance occurs 11 minutes into the film. He is seen carrying a double bass as he climbs onto a train.
Hitchcock said that correct casting saved him "a reel of storytelling time", since audiences would sense qualities in the actors that did not have to be spelled out.[4] Hitchcock said that he originally wanted William Holden for the Guy Haines role,[5][6] but Holden declined. "Holden would have been all wrong—too sturdy, too put off by Bruno", wrote critic Roger Ebert.[4] "Granger is softer and more elusive, more convincing as he tries to slip out of Bruno's conversational web instead of flatly rejecting him."[4]
Warner Bros. wanted their own stars, already under contract, cast wherever possible. In the casting of Anne Morton, Jack L. Warner got what he wanted when he assigned Ruth Roman to the project, over Hitchcock's objections.[7] The director found her "bristling" and "lacking in sex appeal" and said that she had been "foisted upon him."[8] Perhaps it was the circumstances of her forced casting, but Roman became the target of Hitchcock's scorn throughout the production.[9] Granger described Hitchcock's attitude toward Roman as "disinterest" in the actress, and said he saw Hitchcock treat Edith Evanson the same way on the set of Rope (1948). "He had to have one person in each film he could harass," Granger said.[9]
Kasey Rogers (credited as Laura Elliott) noted that she had perfect vision at the time the movie was made, but Hitchcock insisted she wear the character's thick eyeglasses, even in long shots when regular glass lenses would have been undetectable. Rogers was effectively blind with the glasses on and needed to be guided by the other actors.[10]
