The Golden X is a character and Super Smash Bros. Golden X. He plays a major role in the adventure mode and has extremely strong powers and abilites.
Role in the The Return of Tabuu
In adventure mode, the Smasher team of Mario, Pit, and Kirby are the first to hear about the Golden X's Legend. The two find a gold book and a gold map toward the X Temple, where the Golden X rests. The two agree that they must spread the word to every Smasher (except those in the Subspace Army). Kirby points to a stadium in the distance, the second Smasher Stadium. Link and Yoshi are also headed for the same location, and the two teams meet at the stadium; and team up when Mario tells them about the legend. Eventually, all the good Smashers hear about it, and before they go into Subspace, all end up at the X Temple as one large team. When the X meets with the Smashers, he creates Smash Balls for the Smashers to use at will, which spread all around Smashworld.
He is later seen in Subspace after Tabuu turns all of the Smashers into trophy form. He destroys the Sword of Creation and turns all of the Smashers into living form via his special Light Cannon, as well as creating more Smash Balls for the Smashers as they go through Tabuu's Castle