Mystery Assassin

The Mystery Assassin is just that: a mystery assassin working separate from the PPC. His (as the Multiverse Monitor reports, the Mystery Assassin seems to be a male, and possibly a Gary Stu, though he's supposedly claimed his name to be "Alexandra Ward") agenda is unclear, but he has been shown to be hostile to both Mary Sues and PPC agents, sweeping into the badfic to quickly kill the Sue before agents can charge and assassinate, and then occasionally fight or otherwise hinder the Agents before leaving. He has been reported to throw them out of character from time to time, and even hound agents deemed "unworthy" into exile or even madness. He has also been reported to occasionally attack canons under the impression that they are Sues. During the Multiverse Monitor's run, the Department of Internal Affairs were investigating him, but it's unknown if this is still the case.

First reports and theories
Recently, a new theory about this shadowy figure has been produced. The theorists suggest that he may be a fanwriter who was targeted by the PPC. On finding this out, he thought up a rather convoluted plot, determined to get revenge on the people who killed his fics and prove he was better than them at Sue-killing at the same time.

He deleted his fics and changed his entire internet persona. Then, he volunteered to join the PPC (possibly around 2001/2002, when mission reports started getting onto the internet) and became an Agent. He remained rather low-key for a year or two, learning as much as he could, before choosing a time to kill his partner and set himself up as a competitor to the PPC.

He did this by causing an accident in a mission which killed his partner, the Sue they were after, and a copy of himself which he created with a Simulation Generator (which he had stolen from DoSAT just beforehand). Then he fled into the Word Worlds, although he was reported KIA. A little while later, he began invading other Agents’ missions and establishing himself as a pain in the backside the Mystery Assassin.

A rambling letter sent to Suicide and Diocletian's RC reveals that the Mystery Assassin considers himself an Agent even after leaving the PPC and sees the other Agents as being too soft to kill Sues on the spot.