Well, over the years he's been plumber, carpenter, animal trainer demolitions worker, soldier, doctor, hotel manager, several dozen varieties of professional athlete, professional wrestler (which is as much acting as it is athleticism), several varieties of racecar driver, referee, artist, martial artist, astronaut, dinosaur-boy (like a cowboy, but for dinosaurs), hazardous waste cleanup professional, toymaker, themepark manager, chef, fighter pilot, big game hunter, and sailor, to say nothing of the fact that he's been acting as de facto prince consort of the Mushroom Kingdom for decades.
It was only a matter of time before he tried his hand at 'serial killer'.