Jean-Paul Belmondo as Arthur Lespinasse

Bourvil as Anatole

David Niven as Colonnel Carol Matthews, aka 'Le Cerveau'

Eli Wallach as Frankie Scannapieco, godfather of the Italian mafia

Silvia Monti as Sofia Scannapieco, Frankie's sister

Raymond Gérôme as Commissioner

Fernand Guiot as Inspector Mazurel, assistant to the commissioner

Jacques Balutin as Inspector Pochet

Jacques Ciron as Inspector Dubœuf

Patrick Préjean as Belgian Sergeant of the armoured car

Robert Dalban as Belgian soldier of the armored car (with a cold)

Raoul Delfosse as Belgian soldier of the armored car

Roland Monk as Belgian soldier of the armored car

Mario David as Jean-François, antique dealer in Le Havre

Henri Génès as Chief warden of Poissy prison

Yves Barsacq as Warden of Poissy prison

Dominique Zardi as Warden of Poissy prison

Max Montavon as Antique dealer in Le Havre, Jean-François’ partner

Paul Mercey as André, the flooded owner of the 5th floor

Henri Attal as Member of the Colonel's gang

Tommy Duggan as Superintendent Cummings

Sophie Grimaldi as Blonde on the train

Roger Lumont as Boss of the shop

John Rico as Member of the Italian mafia

Arch Taylor as Member of the Italian mafia

Trevor A. Stephens as

Pierre Tornade as Belgian soldier of the armored car

Micha Bayard as André's wife

Gérard Hernandez as Policeman in Le Havre

César Torres as (uncredited)

Yvon Dihé as (uncredited)

Arthur Mullard as Spectator watching the news bulletin.