The Queen of Chaos is a demon lord from Dungeons and Dragons - as a chaotic evil entity she is very much a villain and has the upper torso of a corpulent, blue-skinned humanoid female, whereas her lower body is a mass of ten mauve tentacles. Hidden in the tentacles is a razor sharp parrot-like beak. The Queen has long drooping locks of green hair, and she wears a sahuagin skull as a crown. Her weapon of choice is a huge trident.
The Queen of Chaos is an obyrith who rose to power in the Age Before Ages. While the obyrith plotted and warred amongst themslves, the Queen alone looked past the Abyss and discovered life in other planes of existence. Some of this life, namely the souls of the Chaotic Evil dead, seeped into the Abyss, which the obyrith shaped into the tanar'ri. The Queen of Chaos decided to launch a war to conquer the multiverse and rallied all of the obyrith lords to her cause. Those who refused she set an example of by either killing or banishing them. The only exception to this was Dagon, whose power she feared.
Eventually, the Queen took as her consort a tanar'ri demon lord called Miska the Wolf-Spider, and made him head general of her army. With Miska in command, she practically guaranteed the cooperation of the treacherous tanar'ri. She murdered the then-Prince of Demons, Obox-ob, and bestowed his title on Miska.
The Queen of Chaos, with Miska in tow, was triumphant as the forces of Chaos swept the multiverse. Opposing them were the forces of Law, led by the Wind Dukes of Aaqa, the Vaati. Eventually, the Vaati fashioned the Rod of Law, and with it defeated Miska, banishing him to Pandemonium.
With Miska's defeat, the obyrith alliance fractured. To make matters worse, the tanar'ri revolted and the celestials of the Upper Planes took advantage of the situation and launched an invasion into the Abyss. The obyrith were reduced to near-extinction and the Queen of Chaos withdrew into the 14th layer of the Abyss, known as the Steaming Fen, where she remains to this day, seeking ways to free Miska and restart the war.