Creet

Creet was a young human boy who grew up on the planet of Malcassairo, and was due to fly to Utopia. He helped out at the refugee base. The Doctor made it so the TARDIS could only travel between its previous destination, and the year one hundred trillion (100,000,000,000,000), give or take three years. The Master took the TARDIS and travelled to Utopia. Afterwards, he turned it into a paradox machine. When the paradox machine allowed the Toclafane through a rift in time and space, they were able to kill their human ancestors, because the machine was able to hold the paradox. Martha Jones, Thomas Milligan, and Professer Alison Docherty set a trap for the Toclafane by using a powerful electric current to bring it down, just like Martha saw with lightning when she travelled the world. They open it up, and see a distorted human-like face, surrounded by machinery. When the Toclafane talks about the 'skies being made of diamonds', she remembers Creet saying this about Utopia, and realises that the Toclafane are humans. When the paradox machine is destroyed, the Toclafane are trapped at the other side of the universe.