The Jumbo Ghost
|First appearance||Luigi's Mansion|
|Effective weapon(s)||Poltergust 3000|
Boolossus is the product of 15 Boos fusing together. Luigi must lure the gargantuan into a large unicorn statue's horn sending the then seperated Boos flying for Luigi to freeze with the ice element and vacuum. Once all of the ghosts are caught, the battle is over.