TERILEPTILS

Planet of origin: Terileptus

A Reptilian humanoid species. They developed an advanced space faring civilisation with a high aesthetic sense and some mild warlike tendencies. Although they can breathe oxygen, they cannot survive long without breathing soliton gas, which is highly combustible when combined with it. They are known to employ androids and to prefer forced labour (mainly in the tinclavic mines of the planet Raaga) to the death penalty.

In 1666, a group of Terileptil prison escapees took refuge on Earth in the London area and attempted to use a genetically enhanced version of the Black Plague to destroy humanity. This plan was thwarted and their lab in Pudding Lane destroyed but the event nevertheless caused the Great Fire of London.

Source: Doctor Who, The Visitation (Eric Saward)