Devils (D&D)

Devils are a recurring high-level antagonistic force in Dungeons & Dragons, being the Lawful Evil opposite of the Chaotic Evil Demons - whom they are at near-constant war with and thus both utilize mortal souls as a means to try and win the war, it is believed by many sources that if either Devils or Demons won the war the end of all realms would begin as the victor would finally have the power to flood all other realms with their particular branch of evil.

Devils are a type of Fiend (just like their hated enemy, the Demons) and reside in the Nine Hells - a realm that embodies lawful evil, as such all inhabitants of said realm are also included towards lawful evil behavior and ideals.

This makes Devils natural bullies, slavers and taskmasters who seek conquest and oppression but do so in a methodical pattern - they will make deals with others (as long as the deals are in their own favor) and obey the orders of those stronger than themselves, at least until they can find a means to gain power themselves (again, within the "rules" of lawful evil).

The inclusion of Devils (alongside Demons) in early editions of Dragons & Dragons contributed to the false assumption by certain groups that the game was actually Satanic in nature - this panic caused Wizards of the Coast to lower the appearance / references to Devils and Demons for a short while but as of the modern edition they are back as one of the most prominent threats higher-level parties may encounter.