Xarantharax

The Xarantharax were an alien race created from the imagination of a boy named Harry. Martha Jones encountered them while travelling with the Tenth Doctor.

Biology
The Xarantharax were a humanoid race. They vaguely resembled squids, with multiple tentacles protruding from their faces, and in place of their arms. Their skin was a brown-red colour, and they had large eyes, probably black in colour. They appeared to be allergic to perfume. They could have been amphibious. (DWS: The Box Under the Tree)

History
The Xarantharax were created by the universe, which had observed Harry Ware writing the story of their war with the Iska'lanz'rm. By the 21st century, this war had begun.

In December 2008, the Xarantharax came to Earth to stop Harry from drawing a picture which would end their war and cause the two races to declare peace with eachother. (DWS: The Box Under the Tree)