The Phantom Menace

Depending on which side of the Atlantic you live in, X can either be a lovable, mischievous blonde kid who annoys his neighbor or X might be an uncontrollable schoolboy who enjoys destroying objects, making him more of a villain. Both the comic strips began at the same time and with the same name. Both have been popular in their respective countries although the American version of X is more known world over. Who is X?