Kasterborous

Kasterborous was the star constellation that Gallifrey belonged to. (DW: Voyage of the Damned)

Behind the Scenes
It has been suggested that the design on the back of the Tardis key (Fourth Doctor and Eighth Doctor versions) is a representation of the constellation, with Gallifrey's sun being the central star in the pattern.

Kasterborous is known as 'the Trickster'.