The Witch of Izalith is one of the Lords; deities that defeated the dragons long ago, weaving great firestorms with her many daughters to bring their reign to an end. She is the god of life and of fire, and, accordingly, the godmother of pyromancy. When it became apparent that the Lord Souls would eventually be exhausted, and the Age of Fire would end, the Witch was the first Lord to act - using her mastery of pyromancy, she attempted to recreate the First Flame using a soul. She failed, however, creating what would be known as the Flame of Chaos, an extremely dangerous entity of which she eventually lost control. The chaotic fire engulfed Izalith and the surrounding area, and the Witch was absorbed into the heart of the Flame - the Bed of Chaos, source of all demons. The Witch, or what remains of her, resides within the Bed, no longer resembling anything human.
Two of her daughters managed to escape only partially warped by the Fire: Quelaag, and one known only as The Fair Lady. Their lower bodies morphed into demonic spiders, but their upper bodies were unchanged, and their minds seemingly unaffected. A third, Quelana, managed to escape completely unharmed, and now wanders the Blighttown swamp, and will converse with the player. Her unnamed eldest daughter can be found in the hall before the Bed of Chaos, and is hostile to the player (although reaching this point requires the player to kill at least one of her sisters and her brother, so this may be why). Her only son, unmentioned until the player finds him, was painfully transformed into the being now known as the Ceaseless Discharge, who can be found in the Demon Ruins.