Colony Sarff
Colony Sarff was a servant to Davros comprised of several snake-like creatures. Although acting as an individual, the snakes were able to act independently, but made decisions as a democracy.
Sarff searched for the Twelfth Doctor, travelling to the Maldovarium, the Shadow Proclamation, and Karn where they encountered the Sisterhood of Karn who could stop them from using their powers against them. Whilst unknowingly in the presence of the Doctor, they told Ohila, the Sisterhood's High Priestess, that Davros was searching for him.
Sarff returned to Davros, who told them that in order to find the Time Lord they must first find his friends. They then followed Clara Oswald and Missy to Essex in 1138, where one of the snakes attacked Bors.
They transferred the Doctor, Clara, and Missy (with their hands bound by more snakes) to their spaceship where they travelled to Skaro. They then accompanied the Doctor to see Davros, who asked them to leave. (TV: The Magician's Apprentice)
