Grand Duchess Gloriana XII/Prime Minister Count Rupert Mountjoy/Tully Bascombe
Peter Sellers
Helen Kokintz
Jean Seberg
Will Buckley
William Hartnell
Professor Alfred Kokintz
David Kossoff
Benter
Leo McKern
Roger
Timothy Bateson
General Snippet
MacDonald Parke
United States Secretary of Defense
Austin Willis
Cobbley
Monty Landis
Pedro
Harold Kasket
Pedro
Harold Kasket
Air Raid Warden
Alan Gifford
BBC Announcer
Colin Gordon
O'Hara
George Margo
Ticket Collector (uncredited)
Jacques Cey
Mulligan
Robin Gatehouse
U.S. Policeman (uncredited)
Bill Nagy
Soviet Ambassador (uncredited)
Guy Deghy
Telephone Operator (scenes deleted)
Mavis Villiers
Spectator (uncredited)
Eve Eden
Cunard Captain
Stuart Saunders
Ken Stanley
Army Captain (uncredited)
Bill Edwards
US Policeman
Bill Nagy
Ada - Lady in Waiting (uncredited)
Mabel Etherington
Telephone Operator
Mavis Villiers
Lady in Waiting (uncredited)
Muriel Greenslade
Fenwickian (uncredited)
Fred Haggerty
British Ambassador
Charles Clay
French Ambassador
Henry de Bray
Maybury (uncredited)
Juba Kennerley
Billy Edwards
American General at the Pentagon (uncredited)
Lionel Murton
Reporter (uncredited)
Robert O'Neill
American General (uncredited)
Pat Ryan
Chester Beston
Larry Cross
Fenwickian (uncredited)
Fred Stroud
American Admiral (uncredited)
John Tatum
Air Raid Warden in Physics Lab
Wally Brown
Bird Seller (uncredited)
Fred Wood
Reporter
Robert O'Neil