Tabuu is the entity that resides in the Subspace that wishes to tear the Super Smash Bros. world into pieces and drag it into his. He appears as the main antagonist in the Subspace Emissary adventure mode of Super Smash Bros. Brawl.
A Christmas Bizarro
Toad and General Scales took Xigbar to Tabuu, who chains him up for torture while he sings Oogie boogie's song.
He and other villains was chased away, but stays with Zant and General Scales.