<Li> Debbie Reynolds as Kathy Selden . Directors Gene Kelly and Stanley Donen insisted that Reynolds was always first in their minds for the role . Although the film revolves around the idea that Kathy has to dub over for Lina's voice, in the scene where Kathy is dubbing a line of Lina's dialogue ("Our love will last' til the stars turn cold"), Jean Hagen's normal voice is used . </Li> <Li> Donald O'Connor as Cosmo Brown, Don's lifelong pal, and vaudeville partner, who becomes the head of Monumental Pictures' music department . </Li> <Li> Jean Hagen as Lina Lamont . Fresh off her role in The Asphalt Jungle, Hagen read for the part for producer Arthur Freed . She did a dead - on impression of Judy Holliday's Billie Dawn character from Born Yesterday, which won her the role . </Li> <Li> Millard Mitchell as R.F. Simpson . The initials of the fictional head of Monumental Pictures are a reference to producer Arthur Freed . R.F. also uses one of Freed's favorite expressions when he says that he "cannot quite visualize it" and has to see it on film first, referring to the "Broadway Melody" sequence . This is a joke, since the audience has just seen it . </Li>

Who played lina in singing in the rain