Notice: This article uses content directly taken from the Sybil article at the Vampire Diaries Wiki, and is licensed under the Creative Commons Attribution-Share Alike License.
Sybil, initially known as the Armory's Monster, was first introduced in the season finale of the seventh season and was the main antagonist of the eighth season of The Vampire Diaries. Though after her release and through clues left by Enzo, Bonnie was able to deduce that the creature is actually a Siren, as it corrupts and enslaves those that cross its path, feeding off of the darkness in a person's soul as well as devouring their flesh for sustenance. Sybil states that she is tasked with harvesting evil souls, and has enslaved Damon and Enzo to assist her. She has a connection to a mystical symbol and weapon thought to originate from Hell.
Sybil also revealed that she is the younger adoptive sister of a second Siren named Seline.