Rupert Pupkin
Jerry Langford
Rita Keane
Masha
Ed Herlihy
Band Leader
Stage Door Fan
Stage Door Guard
Chauffeur
Young Girl
Autograph Seeker
Caricaturist
Rupert's Mom (voice)
Dolores
Man in Chinese Restaurant (as Chuck L. Low)
Liza Minnelli (credit only)
Roberta Posner
Man at Telephone
Receptionist
Mr. Gangemi
Cathy Long
Street Scum
Street Scum (as Paul Simmion)
Street Scum (as Kosmo Vynil)
Street Scum (as Dom Letts)
Cabbie
Woman in Telephone Booth
Dr. Joyce Brothers (as Dr. Joyce Brothers)
Mystery Guest
Victor Borge
Raymond Wirtz
Security Guard
Jonno
Cook
Audrey
Bert Thomas (as Fred De Cordova)
Wilson Crockett
Gerrity
Giardello
Captain Burke
Langford's Lawyer
Langford's Agent (as Harry Ufland)
Crockett's Secretary
Ticket Taker
Clarence McCabe
McCabe's Wife
Plainclothesman
Plainclothesman (as Jerry Murphy)
Stage Manager
TV Director
Tony Randall
First Man at Bar
Second Man at Bar
Newsman (voice) (as William Jorgensen)
Newsman (voice)
Announcer (voice)
Audience Member (uncredited)
Office Assistant (uncredited)
Girlfriend at Bar (uncredited)
Joe - Talk Show Stagehand (uncredited)
Extra in crowd scene (uncredited)
Waiter (uncredited)
Man on Street (uncredited)
Talk Show Contestant (uncredited)