The GREATEST ninja of all time!!!
1. He can't be seen
2. Only a true ninja can break into that many houses, undetected, in one night
3. He taught reindeer to hover and fly, and we all know that, while only superheros and ninja can fly, only a ninja can teach other lifeforms to do it too... that's right, the reindeer had to become ninjas too.
Kid: I'm gonna stay up and try to see Santa Claus :D
Brother: No!!! don't do that!!! I heard, that the reason his suit is red is from the blood of children trying to sneak a peek at him...
Kid: Huh? Santa kills you if you see him?
Brother: He HAS to! It's the code of the ninja! They're not supposed to be seen. You see them; they kill you!