Kyuss

Kyuss is a demigod of the undead in the Dungeons & Dragons Greyhawk setting, and also a 80's stoner rock band that went on to be the Queens of the Stone Age.

Kyuss's faithful believe that life is obscene, death offers only nothingness and that undeath is the only worthwhile goal. Followers of Kyuss are encouraged to create undead far and wide. They are permitted to control them if necessary, but encouraged to set them free to do as they will when their creators have no further use. Undead are sacred to Kyuss, and his followers are not permitted to destroy them except in self-defense.

Kyuss was a priest of Nerull who sacrificed all his friends, family and followers to please his god. Unfortunately for him, his reward was to have his essence bound into a stone obelisk and abandoned at the bottom of a deep, dark worm-filled fissure (just as planned), because it turns out evil gods don't like having their authority challenged. That didn't stop Kyuss getting a Dracolich (dragotha) and vampire silver dragon (Lashonna) as followers, and creating the Ebon Triad as a front for his cult (simultaneously pissing off basically every evil god of significance) though.

Kyuss is mostly famous for the Sons of Kyuss, a monster from the first edition Fiend folio. They are walking, worm-filled undead, that attempt to burrow into living things. Worms are something of a theme for Kyuss. He appears in the 3e book Elder Evils, where he stands on the cover and appears as one of the nine Evils inside. In the adventure a cultist is trying to free Kyuss by touching his prison with a Sphere of Annihilation. Said cultist pilfered this Sphere from the Tomb of Horrors.