From a funtrivia quiz I just did:
10. If you wanted to spoil a film about a novice warrior and his evil nemesis by saying "It's his dad." What movie would that be?
Your Answer: The Empire Strikes Back
Take away the bad guy's mysterious alias and he's got the same silly last name as the kid. To be fair this ending has been ruined by the filmmaker himself by making more films with the same characters.