Paolo Panelli as X1

Carlo Croccolo as X4

Enzo Garinei as X3

Alfredo Landa as X2

Magali Noël as Matilde Bernabei

Ciccio Ingrassia as Lo scrittore di fantascienza

Franco Franchi as Socio dello scrittore

Pietro De Vico as Cameriere d'Hotel

Valeria Fabrizi as Cameriera d'Hotel

Nando Martellini as Se stesso

Umberto D'Orsi as L'editore

Riccardo Billi as Tifoso di calcio

Francesco Mulè as Ambasciatore austriaco

Lando Buzzanca as Lo sposo

Mario De Simone as Passante che parla con X1

Margaret Lee as Segretaria dell'editore

Tullio Altamura as Professore di matematica

Nerio Bernardi as Sottosegretario esteri

Dominique Boschero as La sposa

Alicia Brandet as Frida, cantante lirica

José Calvo as Marito geloso

Eva Darin as

Thea Fleming as

Agata Flori as Ragazza in bikini

Jenny Folchi as

Corinne Fontaine as Ragazza francese

Cristina Gaïoni as Figlia del contadino

Aldo Giuffrè as Il protettore di prostitute

Annie Gorassini as Ragazza in bikini

Margaret Rose Keil as

Salvo Libassi as Salumiere

Rosemarie Lindt as

Mimmo Poli as Tifoso allo stadio

Lucia Modugno as

Bruno Scipioni as

Seyna Seyn as Ragazza asiatica

Alfredo Tasso as

José María Tasso as

Elena María Tejeiro as

Ángel Ter as

Pietro Tordi as Contadino abruzzese

Renato Turi as La Grande Mente (voice)

Max Turilli as Segretario dell'ambasciatore

Raimondo Vianello as

Jimmy il Fenomeno as Venditore di bibite allo stadio (uncredited)

Nico Rienzi as Narratore (uncredited)

Rossana Canghiari as Party Guest (uncredited)