Surgeon (The End of the World)

The Surgeons were two people of unknown origin and race.

They are covered with white suits that cover their faces so. They look human but are not, seeing as Lady Cassandra O'Brien is the last human at that time. They work for Cassandra by spraying her with water to keep her alive.

They appeared to be just employees of hers, until she threatened the Doctor that he would be sprayed with acid by them. When Cassandra teleported away the surgeons came with her, but when the Doctor teleported her back, they stayed at the destination, where ever it was. This was a mistake for Cassandra, as when she teleported back they didn't, leading to her death. (DW: The End of the World)