Slitheen

The Slitheen are a family of massive, bipedal extraterrestrials from the British science fiction television series Doctor Who and are adversaries of the Doctor. They first appeared in the 2005 series episodes "Aliens of London" and "World War Three", and subsequently recur in later episodes of both Doctor Who and spin-off series The Sarah Jane Adventures. They are creatures of living calcium, hatched from eggs and native to the planet Raxacoricofallapatorius. Though the name "Slitheen" refers to a specific family, the term has been used by the Doctor and Rose to refer to the Raxacoricofallapatorian race in general.

The Slitheen are a ruthless criminal sect whose main motivation is profit. They are instinctive hunters, being trained to hunt and kill from a young age. The members of the family are convicted criminals on their planet, subject to the death penalty if captured.