Here’s an obscure performer who, I’d guess, must be an American: the marvellously named Jim Granite!
Who was he? Well, as far as I can tell he only appeared in one film, Carlo Lizzani’s Il gobbo (1960). He plays a young American soldier who comes to the assistance of Anna Maria Ferrero, only to be chased off by Pier Paolo Pasolini (who plays an angry, one armed, ex-partisan). He has a total of about two minutes of screentime, but it’s not an unimportant role and he has a good few lines of dialogue (spoken in English).