Abaddon, aka Ubilaz, is a powerful demon known for causing chaos and destruction.
Abbadon's origin remains a mystery, but it is known that the second generation circle, more specifically Dawn Chamberlain, summoned Abbadon 16 years before the third generation circle. It is thought that the circle wanted to use Abbadon to gain more power. At some point, Abbadon possesed Heather Barnes, the best friend of Amelia Blake. Abbadon was trapped inside Heather for sixteen years after Amelia used a suppresion spell on Heather. Abbadon was then freed by Cassie Blake and Faye Chamberlain using circle magic. After awaking, Heather, carrying Abbadon, went to look for Amelia, however, she found Faye and Cassie. Abbadon left Heather after the vessel was killed in a car accident, taking the new form of Melissa Glaser. While possessing Melissa, Abaddon tried freeing the other demons, presumably summoned at the same time as himself, his attempts were thwarted by Jane Blake, a powerful Elder. Following this, Abaddon possessed Nick Armstrong and was drowned and killed by Charles Meade.
- Fire: A substance of fuel that is extremely lethal to Demons.
- Crystals: Demons are weakened by the forces of magic and witchcraft, especially magic crystals.
- Water: A substance of liquid that is extremely lethal to Demons.