Skeletoid

The Skeletoids were suits which could take over their wearers. They required a living Human in order to function. These Humans would be mind-controlled and preserved by the suit, though they would 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)

Behind the scenes

 * 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.