Gene Kelly headlines as dashing silent movie star Don Lockwood. His show-stopping performance of the title song is an iconic movie moment. Donald O'Connor plays Don's partner Cosmo Brown, who in a comic role nearly steals the film. His running-up-a-wall somersault in "Make Em Laugh" is an audience favorite. Debbie Reynolds plays the aspiring young actress and love interest Kathy Seldon. She was only 19 at the time.
Jean Hagen plays the screechy-voiced Lina Lamont, who is eventually upstaged by the Debbie Reynolds character. She was nominated for Best Supporting Actress, one of only two Oscar nods for the movie. Millard Mitchell plays the studio chief R.F. Simpson. Cyd Charisse, in a break-out role, played a long-legged, green-clad dancer who pairs with Kelly in one of the movie's final sequences. Rita Moreno plays Zelda Zanders, a small but substantial role that would pave the way for later starring roles in "The King and I" and "West Side Story." Douglas Fowley rounds out the supporting cast as director Roscoe Dexter.
The large uncredited cast includes dozens of chorus boys and girls. One was Sylvia Lewis, who is among the tango dancers. She went on to a long career that included guest appearances on TV shows like "Married ...With Children." Other notable uncredited appearances include Robert Fortier as a gangster in one of the closing musical numbers.
In the story, the Reynolds character dubs the supposedly shrill vocals of the Hagen character. In fact, Hagen had a beautiful and resonant voice. So, in some scenes, Reynolds appears to be dubbing for Hagen but in fact it is the other way around. In musical numbers like "Would You?" it is Betty Noyes, and not Reynolds, who dubs Hagen's vocals.