Swag King Boo is a very ugly and greedy Boo from Super Mario Sunshine. He is the king of the Sunshine Realm and he hates the other guy with the same name. He spends a large part of his life on playing Slot Machines and Roulette. In The Only Elmo in Grouchland Poop Anyone Has Ever Made, it was revealed that he has an interest in opening casinos, as he wants to turn Sesame Street into a casino.
- Many people think that the other King Boo is him in Super Mario Sunshine, but it's false.
- He was made by Bowser Jr., despite the fact that he banned Bowser Jr. from his realm.