After meeting his end, the Zombie King roams around the dreadful surface of the volcanic planet Tyranus where the Black Skeleton King also dwells. In the Deadland region, he commands a massive army of Zombie Knights and Soldiers and once started a zombie apocalypse at one point.
Grand Interdimensional War
When Grand Emperor Enoch first broke ground in Tyranus, he became loyal to him. He, along with the Black Skeleton King, joined his army in hopes of winning.
Fate of the Multiverse
He is one of the two undead bosses to be fought outside of Enoch's Castle. Gandalf and Albus Dumbledore battled the king and defeat him, making him the first undead boss to be defeated, second to the Black Skeleton King.
After Enoch's ultimate defeat, his zombies along with the Black Skeletons perished in the destruction of Tyranus.