Clockwork Droid
The Clockwork Repair Droids were androids who stalked Madame de Pompadour in 18th century France, believing that in taking her brain, they could repair their ship. They wore 18th century French clothing to blend in with the guests at the French-ball, and were clockwork instead of electric so they could function if their ship's power was depleted.
The Droids began as repair robots onboard the spaceship SS Madame De Pompadour in the 51st century. Their only purpose was to fix the ship if broke down. When the ship was damaged in the Dagmar Cluster due to an Ion storm, they did not have the right parts and so they used the 50 crew members, using their body parts to repair the ship. The last part they needed was a brain for their command circuit, and they believed that only a 37-year-old brain (the same age of their ship) would work. They modified the ship's quantum drive to open multiple time windows to 18th century France and passed through it at various stages of Madame de Pompadour's life, attempting to find her in her 37th year.
They followed camouflage procedures to blend into the surroundings by dressing in somewhat unrealistic 18th century costumes. They were equipped with short range teleporters, scanners, tranquilizers and sharp tools within their wristes for part removal
. They could also heat themselves up if they ever got frozen and empty unwanted fluids out of their system. Whenever they entered a room, they made unnerving 'tick tock' noises from their clockwork parts, which means they often broke any clock in the room to avoid raising suspicion. The Doctor defeated them by disconnecting the time window that led back to their ship, which caused them to shut down from lack of purpose. (DW: The Girl in the Fireplace)
Other Clockwork Droids
The Doctor encountered a different type of clockwork android during his ninth incarnation. Shade Vassily made an almost perfect human-looking clockwork droid (Repple) so that he can distract anyone who comes looking for him, but the Doctor figured out he was clockwork. Clockwork Cats which shot lasers from of their eyes protected Vassily, but the Doctor and Malisa Heart reprogrammed one. Malisa also used two clockwork knights to do her bidding, both of which were destroyed; one was used to repair the clockwork cat, and the other sacrificed itself to save London. (NSA: The Clockwise Man)
