Baatezu

The lawful evil badguys from another dimension, in Advanced Dungeons & Dragons 2nd edition.

Formerly known as "devils." Their home was once called "the nine hells," but now it's "Baator," but each of the nine levels still has the same names from Dante's Inferno.

You can blame this mess on one-time CEO of TSR Lorraine Williams, for caving into Jack Chick and his ilk to force the renaming.

The term "Baatezu" is a trademark of TSR Wizards Of The Coast, so you won't find them mentioned in any Open License products like the d20 SRD nor Pathfinder.

Baatezu represent the lawful side of evil. The concept that cruelty and malice should be distributed in an orderly and efficient fashion. Backstabbers, vicious politicians and cruel warlords can opt to become petitioners in the "nine hells". You start off as a Lemure or a Nupperibo- Both disgusting parodies of a humanoid with flappy and fatty skin. If you please your dark lords enough, you may be promoted to a Spinagon, a grotesque, spiny gargoyle-esque monster. From stage to stage, you start looking more and more like your horrible masters.