Arsène Lupin, fictional character in stories and novels by Maurice Leblanc. The debonair Lupin is a reformed thief, a criminal genius who has turned detective. The police are not convinced of his change of heart and often suspect him when a daring robbery occurs. Among the actors who have played Lupin, or characters inspired by him, are John Barrymore, Georges Descrières, Romain Duris. and Omar Sy.