- “Defilers! I'll...cut you into nothing! I'll feast on your brains. I'll swim in lakes of your own blood!”
- ―Matthias Pavayne[src]
Matthias Pavayne is an 18th century European aristocrat. He is a doctor that was nicknamed the Reaper for performing unnecessary (and fatal) surgeries on his patients. When word spread of his unorthodox practices, he escaped to California. His arrival at that time coincided with a rash of brutal, ritualistic murders; pieces of the victims placed in such a manner that suggested an intimate knowledge of the dark arts.
The murders continued for nearly twenty years, until in 1791, representatives from Wolfram & Hart were looking to build a new branch in what would eventually become Los Angeles. Unfortunately a Spanish mission was already resting on the site their seers recommended. They needed an appropriate sacrifice to deconsecrate the ground; Pavayne's blood suited the needs of the situation, and Pavayne was killed by Wolfram and Hart.
From this point on, Pavayne's ghost haunts the Los Angeles branch of Wolfram & Hart by stealing the souls of any employee that dies in service of the company, tortures their souls until he has his fill, then sacrifices them through a portal to Hell that he opens, in order to circumvent having to go himself.
In October of 2003, he turns his attention towards sending Spike (currently trapped in a ghost-like state after his battle with the First) to Hell in his place, torturing him with ghosts as the team race against time to attempt an experiment that will make Spike corporeal again. However, just as he is about to send Spike to Hell, Spike learns how to manipulate his environment so that he can fight back against Pavayne, managing to keep the doctor occupied until the machine is completed. Although Pavayne threatens to kill Fred before Spike can use the machine, Spike instead sacrifices his chance to become corporeal again by throwing Pavayne into the machine, restoring him to a solid form. With Pavayne now in an apparently immortal but otherwise physically human body, Angel defeats him and then arranges for him to be kept in a special Wolfram & Hart containment unit, the unit being a small box which leaves Pavayne in apparent suspended animation, with just enough room to stand while leaving him unable to move, speak, or affect the world around him, his only reprive from the torment being a window of the corridor outside his cell.
Due to the destruction of the L.A. Wolfram & Hart building in "Not Fade Away", it seems likely that Pavayne died in the collapse.