Tanar'ri

These are demons, the chaotic evil supernatural badguys, in Advanced Dungeons & Dragons 2nd edition.

Y'see, after TSR kicked out Gary Gygax, the new CEO Lorraine Williams decided that nutcases like Jack Chick and Patricia Pulling had to be pandered to, so Williams said "no more demons, or any of that junk. Oh, and get rid of orcs as a playable race, because they're ugly. Ewww." It's marketing genius like this that drove TSR into the ground so that some dinky company whose only product was a card game could step in and buy them out.