Weevil

A vicious alien species from the Doctor Who spin-off, Torchwood, the Weevils' origins (planet, species, etc.) are unknown. The only knowledge acquired is the fact that they, like a lot of other remnants of various extra-terrestrial life and technology gathered by Torchwood, did not come to this planet on any form of ship or teleporter, but were spilled onto this planet from the dimensional rift running directly through Cardiff, Wales, where the Torchwood-3 facility (helmed by Captain Jack Harkness) is stationed to monitor and contain rift activity. Upon a Weevil's arrival, they generally migrate to the sewage systems and keep out of sight. Unfortunately, Weevils are carnivorous and tend to occassionally wander to the surface to prey on innocent victims. The Torchwood team can track the Weevils and subdue them with a patented Anti-Weevil spray before encarcerating them in the containment cells at the central hub. It was later discovered that, originating from the rift, Weevils are highly sensitive to temperal activity and can be used to detect spikes in rift anomolies that can be dangerous if left unattended.