Hath

Appearance
In appearance half ??? and humanoid but their skin resembles that of a fish. They wear grey jumpsuits while in battle and brown boots, and they bear green devices to help in combat. They have purple growths on their heads.

History
Hath originated on the planet Messaline, they got into a war against the Humans on Messaline in the search for The Source.

Myths and rumours
It was rumoured Hath are red bubbles that communicate through expanding and letting out smaller bubbles. It was also rumoured one of them will kill Jenny at the end of the episode. Doctor Who Magazine 395 reveals that Hath do communicate through bubbles but are humanoid fish.

Continuity
In the comentary for the last of the time lords David tenant jokes on having an enemy that will be a ball on a stick this enemy may be like that!