Guardian
The Guardian is an enemy from Kingdom Hearts.
Ansem did not battle Sora alone in the End of the World, he used a familar Heartless known as the Guardian. It served as a shield for Ansem during the battles against Sora. It would leap from behind Ansem to block an attack. Eventually, the Guardian transformed into the World of Chaos.
The Guardian resurfaced during Kingdom Hearts 2: Final Mix+, when Riku used the dark powers to defeat Roxas. It no longer makes an appearance after being used to subdue Roxas, as Riku, who only used the darkness as his last resort, elects not to summon it any longer for fear of darkness already eating at him.
Due to its immense power and ability to transform into a much more powerful version, it is possible that it is the most powerful of all heartless. This stems from the fact that some beleive The Guardian to be Ansem's true essense, as it primarily does all the fighting between the pair and even appears to Riku after he opens his heart to Ansem's darkness.
