Terileptil Terileptils were a space - faring reptilian species , known for a love of art and beauty , matched only by their love of war . Biology . Terileptils were reptilian humanoid s , but also had fish - like qualities . Each Terileptil seemed to be of primarily one colour — for example , green , blue or red — but some of their scales and ruffles had variations in hue . Terileptils breathed through gills on the side of the head , their hands and feet were like flippers , and their wide mouths were full of pointy teeth . They breathed soliton gas . ( TV : " The Visitation " ) Technology . Terileptils had a highly sophisticated technology . Dependent on soliton gas , they perfected atmospheric processors which could synthesise and release the gas into the immediate area , allowing them to function in alien atmospheres lacking this vital component . They were familiar with the use of Vintaric crystal s as a means of artificial lighting , and holographic energy barrier s . Terileptilan technology made heavy use of polygrite and highly charged power pack s . They made frequent use of androids as guards , soldiers , and servitors . ( TV : " The Visitation " ) Culture . The Terileptils placed great value on beauty , using aesthetically pleasing designs even in weaponry . Even the Terileptilan language reflected the artistic and scientific sophistication of this species ; to the untrained eye Terileptilan script looked very much like mathematical formulae . As a part of this highly refined culture , the Terileptils esteemed certain vocations , such as mime and circus clown . They considered war an honourable activity and that it stood side by side with art and beauty . Terileptils were allied with the inhabitants of the planet Hakol in the Rifta system , for whom they mine d tinclavic , which was found on the planet Raaga . Condemned criminals were conscripted to mine this mineral , overseen by android guards and wearing control bracelets . Severe facial scarring was a common feature of these conscripts , possibly due to the toxic nature of raw tinclavic ore . ( TV : " The Visitation " ) History . In 102 , the Terileptils were among the races who joined the Alliance . They came to Stonehenge and helped imprison the Eleventh Doctor in the Pandorica in order to save the universe . ( TV : " The Pandorica Opens " ) As early as Earth ' s late Middle Ages , Terileptils mined tinclavic for the people of Hakol . A psychic probe from Hakol landed on Earth at this time , becoming briefly active in the year 1643 and again in 1984 . ( TV : " The Awakening " ) In 1666 , the Fifth Doctor found a small group of Terileptil criminals who had escaped from the penal colony on Raaga . They had somehow managed to override their control bracelet s , reprogram an android guard to help them , and steal a ship . They were caught in an asteroid storm crossing through Earth ' s planetary system . The ship ' s escape pod crashed outside a small village near the future location of Heathrow Airport , with only four Terileptils surviving the crash . The Doctor could not return the creatures to their home planet , because Terileptil law stated that imprisonment on Raaga was for life . Plague was already raging in London , and the three remaining Terileptils began to genetically augment the plague bacteria , plotting to eradicate human ity and seize control of the planet . Their plot failed when the Doctor and his companion s , along with Richard Mace , fought them in a bakery on London ' s Pudding Lane , and a burning torch dropped during the scuffle , together with an overloaded Terileptil hand weapon , resulted in the Great Fire of London , which killed the Terileptils and destroyed their augmented plague bacteria . ( TV : " The Visitation " ) In 3375 , the Adjudicator Terrell and the Master destroyed the Terileptil homeworld using the Darkheart device . Aside from individual Terileptils who may have been elsewhere in the galaxy when this occurred , the species was wiped out . This act ended an interplanetary civilisation more than two thousand years old and was also one of the final steps in the Master ' s descent into darkness . ( PROSE : " The Dark Path " ) Undated events . At some point in their history , the Terileptils went to war with the Torodon . ( PROSE : " Hunter ' s Moon " ) Terileptils were present during the Siege of Trenzalore . They either retreated or died in the fighting which took place after the Dalek s broke through the Papal Mainframe ' s force field and plunged Trenzalore into war . Their forces either retreated or were destroyed before the final battle between the Eleventh Doctor and the Dalek s . ( TV : " The Time of the Doctor " ) A Terileptil was a customer at the Intergalactic Coffee Roasting Station . ( PROSE : " Lights Out " ) Alternate timeline . In an alternate timeline created by the Black Guardian where the First Doctor never left Gallifrey , and became Lord President , the Terileptils were one of many aliens that invaded Earth , and fought over the planet with other races against the Silurian s and the Sea Devil s . This timeline was destroyed when the Seventh Doctor retrieved the Key to Time . ( COMIC : " Time & Time Again " ) References . Tegan and Nyssa saw a hallucination of a Terileptil projected in an attempt to prevent them from entering the Inner Sanctum presided over by Kalid . ( TV : " Time - Flight " ) The Sixth Doctor had a nightmare in which he and Tegan visited Raaga and helped Terileptil slaves construct a time corridor and escape . ( PROSE : " CHAOS " ) The Yssgaroth ' s universe contained the remains of Terileptils who had been brought there . ( PROSE : " The Pit " ) The Seventh Doctor had a Terileptil sculpture in his TARDIS art gallery . Ace thought it looked like a glass factory exploded . ( AUDIO : " Dust Breeding " ) The Twelfth Doctor blamed the Terileptils for the Great Fire of London . ( TV : " The Woman Who Lived " ) River Song mentioned that Terileptils were part of the invading forces in the events of the Pandorica . ( TV : " The Pandorica Opens " ) Other information . When cyborg hacker Psi was attempting to protect Clara Oswald from the Teller , he ensured that it would focus on his guilt by uploading the memories of some of the worst criminals in history , one of them being a Terileptil . ( TV : " Time Heist " ) Behind the scenes . The Terileptil illusion seen in " Time - Flight " part two was played by Chris Bradshaw , who remained uncredited both on - screen and in " Radio Times " . ( DWM 294 )