Skeletoid

The Skeletoids were a type of suits which could take over bodies. They required a living Human in order to function. These Humans are mind controlled and preserved by the suit, though they look like decayed corpses.

They have emerged as a serious threat to even the Daleks and the Cybermen (DWM: Kane's Story, Frobisher's Story)

Trivia

 * It could be argued that there is a similar creature present in Silence in the Library, where creatures called Vashta Nerada ate humans in their spacesuit, leaving only their skeletons, and were able to control of the suit as well.
 * Another similar monster, were the Skeleton Crew from The Infinite Quest.