Zygon

Zygon

The Zygons are a fictional extraterrestrial race in the long-running British science fiction television series Doctor Who. They first appeared in the Fourth Doctor serial Terror of the Zygons, where it was revealed that centuries ago, the Zygon homeworld was destroyed in a stellar explosion. A craft escaped and somehow made it to Earth, where it then crashed into Loch Ness. When the Doctor encountered the Zygons, they were led by a warlord named Broton. Broton wished to conquer the world to allow a refugee fleet of Zygons to colonize Earth.

The Zygons have shape-shifting abilities, allowing them to replicate the appearance of another being, but they must keep the subject alive in order to use its body print. This skill was vital in their concealment and in their scheme to seize power despite their small numbers. The Zygons were also accompanied by an armoured cyborg creature called the Skarasen, the lactic fluid of which was necessary for them to feed. Broton planned to unleash the Skarasen (or Loch Ness Monster as it was known) as part of a bid to conquer the Earth. The plan was foiled and both he and his crew were killed due to the intervention of the Fourth Doctor and the United Nations Intelligence Taskforce (UNIT). Zygon technology is biological in nature: in essence their ships and equipment are actually alive.

David Tennant (the Tenth Doctor) has stated that they are his favourite monsters from Doctor Who.