Zalgo is a form of text formatting associated with creepypasta, demons, and eldritch abominations. It uses various tricks, particularly Unicode combining diacritics and control characters that change the text flow direction. The result is text that appears corrupted, glitchy and partially overwritten by eldritch symbols.
Zalgo text originated in fan edits of the comic strip Garfield, usually containing the phrase "He Comes!".
https://zalgo.org: A text generator used to summon H̶̘̚̚I̵̲̱͗̓M̴͍͈͌