The Terileptils are an advanced race of reptilian humanoids, with a strong appreciation for grace and beauty. Breathing flammable soliton gas, they incorporated elegant design into functional items like their androids, atmosphere propagators and guns. Terileptil prisoners mined tinclavic for the Hakolians – and it was from the tinclavic mines that a group of four Terileptil convicts escaped. Their ship crashed on Earth in the 17th century, where – using a reprogrammed android dressed as Death – they began to develop a super-strain of bubonic plague. They were foiled by the Fifth Doctor, when the soliton and oxygen rich atmosphere in their London command centre combusted. The fire quickly took hold, destroying much of the city, and became known as the Great Fire of London. A Terileptil force was part of the alliance that lured the Eleventh Doctor to Stonehenge and imprisoned him in the Pandorica.