The Weevils are a humanoid alien race who came through the Cardiff rift from their (unknown) homeworld. There are hundreds of them living in the Cardiff sewers, but occasionally one escapes to the surface. Not much more is known about them, not even what they call themselves, since they have trouble communicating with Humans. One of the jobs of the Torchwood 3 is to capture these Weevils when they cuase problems.
Physiology
Weevils are roughly humanoid in shape and size, but are a bit taller and have odd faces with many sharp, fang-like teeth. They are decribed as looking like a Human wearing a very realistic prosthetic mask, which one hospital porter likened to Hellraiser. Though they can overpower a Human, they aren't extraordinarily strong.
Behaviour
Weevils seem to be vicious creatures (as seen when one attacks a police porter) and apparently do not communicate, or if they do, only with grunts and roars.
- Captain Jack Harkness explained that the Weevils do not usually feed on humans, but in the sewers eat "you can guess what".