A Soul Stealer is a specialized Thaumaturgist who is capable of utilizing Outsider based thaumaturgy to consume the essence, life-force, willpower, knowledge and experience of other Thaumaturgists. They are generally very rare, and exceedingly dangerous, as they possess massive amounts of power and knowledge.
As the Soul Stealer consumes the essence of their victims, the victim’s voice is added to that of the original. Thus, as a Soul Stealer grows more successful in their hunting, their voice becomes more and more difficult to understand, as voice-upon-voice is layered upon the original.
It is believed that this aspect makes it difficult for a Thaumaturgist to counter a Soul Stealer’s spells, as they are difficult to interpret or predict. It has been surmised that a Soul Stealer is somehow immune to a Thaumaturgist’s death Curse. It is possible that the thaumaturge consumed by a Soul Stealer is not destroyed or killed, but rather absorbed.
In 1936, a female soul stealer was involved in the kidnap of children from the Our Lady of Mercy Orphanage in Rome. it was believed that she was the leader of a cult and that she was in league with an Outsider known as a Bound Abomination.