Peter Sellers as Aldo Vanucci / Federico Fabrizi

Victor Mature as Tony Powell

Britt Ekland as Gina Vanucci aka "Gina Romantica"

Martin Balsam as Harry

Akim Tamiroff as Okra

Paolo Stoppa as Polio

Tino Buazzelli as Siepi

Mac Ronay as Carlo

Maria Grazia Buccella as Bikini Girl

Lando Buzzanca as Police Chief

Lydia Brazzi as Mamma Vanucci

Vittorio De Sica as Himself

Maurice Denham as Chief of Interpol

Tiberio Murgia as 1st Detective

Francesco De Leone as 2nd Detective

Carlo Croccolo as Cafe Owner

Nino Musco as Mayor

Pier Luigi Pizzi as Doctor

Lino Mattera as Singer

Piero Gerlini as 1st Gaoler

Daniele Vargas as Prosecutor

Franco Sportelli as Judge

Giustino Durano as Critic

Mimmo Poli as Fat Actor

Enzo Fiermonte as Raymond

Angelo Spaggiari as Felix Kessler

Mario Del Vago as Manuel Ortega

Timothy Bateson as Michael O'Reilly

David Lodge as Policeman

Lucia Cavalieri as Bingo Player (uncredited)