This a list of demon lords in the Dungeons & Dragons fantasy role-playing game. In the 2nd Edition, the demon lords were known as "Abyssal lords".
Abraxas, known as the Unfathomable, is the demon lord of magic words, arcane secrets, and talismans, in the Dungeons & Dragons roleplaying game. Abraxas dwells on the 17th layer of the Abyss, known as Death's Reward. Abraxas was one of many demon lords that were mentioned only by name in a list in the original Monster Manual II (1983). His portfolio is given as forbidden lore, magic, and snakes. As in Armies of the Abyss, Abraxas's realm is called the Pleroma here, and it is said to be a superficially pleasant and beautiful realm whose true appearance is masked by illusions. Abraxas rules from the spiral city of Diovengia, which is filled with demons, libraries, and serpents and guarded by mariliths. Instead of the chaste ascetics of Armies of the Abyss, however, his cultists in this book are drow and keepers of forbidden lore who maintain a notorious library and tattoo their greatest secrets on their bodies.
Adimarchus is a Demon lord. He is known as the "Demon Prince of Madness", not because he claimed sovereignty over insanity, but primarily for his current state of mind. Adimarchus made his debut in Dungeon #116 (November 2004) in the adventure Asylum, which is the finale of the Shackled City adventure path. Adimarchus' ultimate fate (whether he lives or dies) depends on what happened in the adventure.
Ahazu the Seizer is a demon lord that now functions as a vestige as a result of his self-imposed imprisonment in the Abyssal layer known as the Wells of Darkness. Ahazu was one of many demon lords that were mentioned only by name in a list in the original Monster Manual II (1983).