The Wraith is the ruler of all soulsuckers, a type of spirit that lives off of the very souls of the weak. Spirits like these include Amelia Astelle, and Fedallah.
The Wraith is a demonic spirit more powerful than Amelia. It can fly, vanish, and go through walls. He can rip open portals in time and space. He can steal the souls of weaker minds.
The Wraith pillaged worlds until he was trapped by his own student, Fedallah, in a holy amulet. The Wraith was eventually freed by Amelia, and killed five people, including Sven Astelle.
The Wraith was captured again, along with Amelia, by Anastasia Tesla, in a holy amulet, until he was freed again by Anastasia.