Rex Harrison as Cecil Fox

Susan Hayward as Mrs. Sheridan

Cliff Robertson as William McFly

Capucine as Princess Dominique

Edie Adams as Merle McGill

Maggie Smith as Sarah Watkins

Adolfo Celi as Inspector Rizzi

Hugh Manning as Volpone

David Dodimead as Mosca

Mimmo Poli as Cook (uncredited)

Luigi Scavran as Massimo (uncredited)

Jack Benny as Violinist Outside Restaurant (uncredited)

Herschel Bernardi as Oscar Ludwig (uncredited) (scenes deleted)

Massimo Serato as The Pretender (uncredited) (scenes deleted)