Devourer

Devourers were fiends who acted in service of Orcus. They were used to create armies of undead by comsuming the bodies and souls of humanoids. Lesser demons could be promoted to devourers by proving themselves to Orcus.

A devourer created new undead by bringing a humanoid creature to the brink of death, and then trapping its victim inside its ribcage. While there, the devourer tortured its victim's soul with telepathic noise until death, after which an undead would come out in its service.