Dalek

The Daleks are ruthless killers from the Doctor Who Canon. Consisting of a mutant lifeform contained in a mechanical 'travel machine', they are one of the most iconic science fiction enemies ever. For more details, see their Wikipedia article.

The Reorganisation
During the Reorganisation, the Department of Internal Security deployed a large, unknown number of Daleks in the halls of HQ in an attempt to defeat the Assassins who were fighting against them. Fortunately for the PPC, Jay Thorntree was able to defeat the Daleks and drive the DIS from HQ.

Multiverse Monitor
The fourth issue of The Multiverse Monitor had a cover story describing the invasion of HQ by another Dalek (a story which caused great distress to Jared Calinson, who had been involved in the repulsion of the former invasion); however, this one turned out to be a foot tall, made of pipecleaners, and was in fact a creation of Agent Flip Finley, named Winston.