C is for... Clockwork Droids

Repair androids used on spaceships in the 51st Century. The SS Madame de Pompadeur was hit by an ion storm and became disabled. The Droids carried out their programming to repair the vessel, and turned to the human survivors for spare parts. The ship's computer needed a replacement part, and they decided to get it from the real Madame De Pompadeur. They opened time windows from the ship to the 18th Century, positioned at various points throughout the woman's life. They would visit her and scan her, waiting for her brain to match the age of the ship, and therefore be compatible with the computer. The Doctor, Rose and Mickey arrived on the ship and found the time windows. The Droids could be disabled by freezing, but recovered quickly and teleported away to safety. They adopted period costumes, with masks, in order to infiltrate the 18th Century. Beneath the masks, their heads were glass globes with clockwork mechanisms within.

Various tools could be extended from their arms, which could also be used as weapons. After identifying the time when Madame de Pompadeur's brain matched the age they wanted, the Doctor cut off their link to 18th Century France. No longer able to complete their task, the Droids deactivated themselves.

The sister ship to the SS Madame de Pompadeur - the SS Marie Antoinette - became disabled after crashing back through time to the prehistoric era on Earth. The Droids of this vessel wanted to become human, so that they could reach a place they called the Promised Land. Their spaceship became buried deep beneath London. They would emerge from the ship to kill people for spare parts. In the Victorian era, they set up a restaurant above the ship, in order to more easily find victims. They were led by a unit which only had half a face. He killed a dinosaur accidentally brought to London by the Doctor, in order to use its optic nerve. The Doctor and Clara found their way to the restaurant and confronted the Half-Face Man. The Droids could be fooled if people held their breath. The ship was attacked by the Paternoster Gang, whilst the police raided the restaurant.

The Half-Face Man tried to flee in an escape capsule - a chamber of the restaurant which was tethered to a balloon made of human skin. The Doctor was also on board. He tried to reason with the Droid, encouraging him to destroy himself. He fell - or was pushed - onto the spire on top of Big Ben. His destruction caused all the other Droids to deactivate. The Half-Face Man suddenly found himself in the Promised Land - really a Gallifreyan Matrix Data-slice controlled by Missy.

Played by: Peter Ferdinando (the Half-Face Man), Graham Duff (the Waiter), Paul Kasey (Clockwork Man), Ellen Thomas (Clockwork Woman). Appearances: The Girl in the Fireplace (2006), Breath (2014).