Hundun

Hundun is an ancient enemy of the Avatar. He wishes to throw the world into chaos, and was an enemy of Korra's after she opened up the spirit portals.

History
Hundun fought against an Avatar many years before 171 AG, and lived in the Spirit World. After the Harmonic Convergence, he entered the physical world and began pursuing his goals of bringing chaos to the world. He was stopped by Korra less than two weeks after entering the physical world.

Trivia

 * Hundun is named after a Chinese chaos entity.