Graske

The Graske were humanoid creatures from the planet Griffoth.

Biology
The Graske were small compared to Humans and had pebbly brown skin and three tentacle-like features on their heads. They could speak Human languages with some difficulty. (DW: Attack of the Graske, SJA: Whatever Happened to Sarah Jane?)

Technology
The Graske were a time-active species and could travel by different methods. Individuals could travel through time with ease, using a device on their belt to vanish in a distinctive blue glow. The Graske employed by the Trickster also had a gun which he could use to take people out of time and put them into Limbo. It could also reverse the process, putting them back in time and space and restoring their timeline. (SJA: Whatever Happened to Sarah Jane?)

When invading a planet, replaced the inhabitants of the planet with changelings. This process was quick, with the Graske replacing the individual with the changeling in seconds. The originals were then stored on Griffoth in stasis chambers in order to maintain the copy. The changeling could be identified by its glowing green eyes. (DW: Attack of the Graske)

History
The Graske were conquerors, though unlike other species they did not take a planet by force. They would instead use their changelings to systematically replace the inhabitants of the planet.

The Graske attempted an invasion of Earth, stealing people from various Christmases from across time, which was stopped by the Doctor and one of his companions by reversing the capturing process, returning the hosts. (DW: Attack of the Graske)

A Graske was also used by the Trickster to remove Sarah Jane Smith and later Maria Jackson from time. The Graske succeeded both times, but Maria managed to escape into 1964. The Graske recaptured her again, but then got sent to capture Alan Jackson. Alan fought the Graske and beat it, forcing it to tell him where his daughter went. The Graske later escaped by wriggling its way out of its bonds. (SJA: Whatever Happened to Sarah Jane?)


 * Sarah Jane believed the Graske was being enslaved by the Trickster, but since the Trickster had no power over people without their assent, the Graske may have been working for him wilfully.