Peter Sellers as Aldo Vanucci/Federico Fabrizi

Victor Mature as Tony Powell

Britt Ekland as Gina Vanucci/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

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

Roberto De Simone as Marcel Vignon

Timothy Bateson as Michael O'Reilly (uncredited)

Ugo Carboni as Pharmacist in Sevalio (uncredited)

Angelo Casadei as Cameraman (uncredited)

Amerigo Castrighella as Via Veneto café costumer (uncredited)

Lucia Cavalieri as Bingo Player (uncredited)

Bruna Cealti as Laundress (uncredited)

Vittorio De Sica as Vittorio De Sica (uncredited)

Carlo Delle Piane as (uncredited)

Daniela Igliozzi as (uncredited)

David Lodge as Police Officer (uncredited)

Cho Cha Lung as Restaurant Patron (uncredited)

Enrico Luzi as Movie Director on Via Veneto (uncredited)

Alba Maiolini as Street Spectator (uncredited)

Maria Grazia Marescalchi as Woman in Sevalio (uncredited)

Valeria Montesi as Pharmacist's Wife (uncredited)

Peggy Nathan as Bingo Player (uncredited)

Carlo Pisacane as 2nd Judge (uncredited)

Marcella Rovena as Salvatore's Wife (uncredited)

Alessandro Tedeschi as Restaurant Customer (uncredited)

Francesco Telli as Child in Sevalio (uncredited)

Nino Vingelli as 3rd Judge (uncredited)