You, Enderman, Skeleton, Zombie, and Spider lived in the overworld.

In the Nether, lived Wither Skeleton, Ghast, Blaze, and Piglin.

One mob could go in all worlds: Herobrine. He was the most powerful mob, and he also looked human. Just with pure white eyes.

"Yo."

Herbrine said, as he walked through the Nether portal, and greeted You, Enderman, Skeleton, Zombie, and Spider.