Zalgo is an Internet legend about an ominous entity believed to cause insanity, death and destruction of the world, similar to the creature Cthulhu created by H.P. Lovecraft in the 1920s. Zalgo is often associated with scrambled text on webpages and photos of people whose eyes and mouth have been covered in black.
Although it's unknown how he forged a Infinity Gauntlet of his own, and how he meet and made the characters Mary, Beldam, Wizeman and Uramiko his followers, it's revealed near the finale that he is a joke among other multiuniversal, powerful entities, and that he wants half of the multiverse to be his through a finger snap so he can have his own respect.
During the movie, as he combats heroes like NiGHTS, Rayman (those first two, the ones to call other heroes to fight him), Sonic the Hedgehog and company, the Crystal Gems and more, he gathers up the Infinity Stones, and succeeds, corrupting half of the multiverse and escaping to his home dimension so he can rest.
In the beginning of Multiverse: Infinity War's sequel, the Zalgo from the current timeline is killed by Kris after being stabbed in the 7th mouth on his back. However, this turns out to be a mistake, as the heroes can't find out until later how to cure the corrupted half of the multiverse (now reduced to mindless, mumbling beings and/or eldritch places).
The true antagonist of the movie is his past self, who gives up on his initial goal of finding respect and simply decides to destroy the multiverse and make another one entirely out of him. This one is also put to a end when NiGHTS sacrifices herself to use the Infinity Stones and put a end to Zlago and his forces.
- Mary † - Enforcer and hinted Friend, later a traitor
- The Beldam † - Enforcer and hinted Friend
- Wizeman the Wicked - Enforcer and hinted Friend
- Uramiko - Enforcer and hinted Friend
- Mary (after she betrays him)
- Rayman - Slave (in the finale)
- Sonic the Hedgehog
- Miles "Tails" Prower
- Knuckles the Echidna
- Amy Rose - Slave (in the finale)
- Cream the Rabbit - Slave (in the finale)
- Steven Universe
- Garnet - Slave (in the finale)
- Ruby and Sapphire - presumably, the same fate of their fusion.
- Peridot - "Victim"
- Kirby - Slave (in the finale)
- Meta Knight - Slave (in the finale)
- King Dedede
- Bandanna Waddle Dee
- Chara - heavily hinted crush but "Victim"
- Dipper Pines
- Mabel Pines
- Pacifica Northwest
- Star Butterfly - Slave (in the finale)
- Pucca - Slave (in the finale)
- Ib - Slave (in the finale)
- Yumi Yoshimura - Slave (in the finale)
- Ami Onuki - Slave (in the finale)
- Cornet Espoir
- Kururu - Slave (in the finale)
- Reala (?) - Victim
- A Swords Knight † - Victim