G is for... Graske

Natives of the planet Griffoth, the Graske are diminutive reptilian creatures which are more mischievous than evil. One of them invaded the TARDIS whilst the Doctor was trying to write a piece of music - later becoming transported to the Royal Albert Hall in the middle of a Proms concert. Previously, they had attempted to take over the Earth by stealth - replacing humans beings with changelings. They had attempted this strategy on other planets.
A Graske named Krislok was saved from his crashing spaceship by the Trickster, who promised him continued life so long as he acted as his servant. The Trickster had Sarah Jane Smith removed from history when he offered her to swap her friend's life for hers back in 1964. Andrea Yates was to have died - but it was Sarah who perished in an accident. The only person who knew that time had been tampered with was Sarah's friend Maria, so Krislok was sent to use a time snare to remove her from time as well.

Maria's father Alan was also immune from the temporal change, and he captured Krislok and forced him to return Maria.
Some time later, the Trickster laid another trap for Sarah. Krislok visited London in 2009 posing as a 1950's schoolboy named Oscar. He pretended to come from the village where Sarah had been born - at the time when her parents had died in a car accident. Clyde and Rani were transported to an alternative 2009 which was ruled over by the Trickster - a world in which Sarah had failed to stop him from breaking through from his own dimension. Krislok was here, acting as a slave worker overseer. He told Clyde and Rani of how the Trickster had forced him into servitude, and agreed to help them return to the correct time line if they gave him the box which protected them from the temporal changes. They accepted the trade, and Krislok was freed as time reasserted itself.

A Graske (possibly Krislok) was present at the bar where the Doctor went in search of Captain Jack Harkness at the end of his tenth incarnation, when he hooked Jack up with Midshipman Frame, late of the spaceship Titanic.
Griffoth had been one of the planets stolen by the Daleks in order to power Davros' Reality Bomb. The Groske are cousins to the Graske, physically identical apart from having blue skin.

Played by: Jimmy Vee. Appearances: Attack of the Graske (2005), SJA 1.4 Whatever Happened To Sarah Jane Smith? (2007), Music of the Spheres (2008), SJA 2.5 The Temptation of Sarah Jane Smith (2008), The End of Time Part 2 (2009).

• Attack of the Graske was an interactive game, written by Gareth Roberts, shown on the BBC's Red Button service immediately following the broadcast of The Christmas Invasion on 25th December 2005. Music of the Spheres was a specially written 7 minute piece made to be screened during the Doctor Who Prom in July 2008.
• The Graske design is based on a jester's hood - indicating their mischievous nature.