Dalek puppet

Dalek puppets were beings who had been taken by the Daleks and partially converted via nanogenes to serve them as slaves.

Biology
The Dalek nanogenes automatically would convert any organism it came in contact with, living or dead, making them into a Dalek puppet. These slaves were used as sleeper agents. When activated, they would have a miniature Dalek eyestalk extend from their forehead and a miniature Dalek gunstick from the palm of their hand. They could also emit a charge that stopped the victim from moving by making contact with them.

Dalek nanoclouds were airborne and invisible, and would slowly convert the victim into an unwitting servant of the Daleks. Not even death could protect victims from this fate: the conversion process worked on dead and living flesh alike, and could turn innocent corpses into shambling, zombie-like creatures. (TV: Asylum of the Daleks) Species susceptible to the process included humans, Sontarans, Judoon and Silents, with only Time Lords being known for immunity. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

Progenitors
More primitive progenitors of the Dalek puppets were the Robomen, who were prisoners on whose brains the Daleks operated in a surgical procedure called the Transfer after being sought after for intelligence and given a drug to make the process more successful, fitting them with large, helmet-like headsets. The Daleks' mind control technique was unstable, and the Robomen would eventually go insane and commit suicide. (TV: The Dalek Invasion of Earth) The eyestalk extending from Dalek puppets' foreheads made them visually reminiscent of Dalek Troopers. (TV: Resurrection of the Daleks)

History
The Dalek puppets were created at the onset of the New Dalek Paradigm. After using a Time-Space Visualiser to study the Robomen of the Dalek Empire, the Strategist Dalek had the Scientist develop the puppets as a more effective means of producing slaves. (PROSE:  The Astounding Untold History of the Greatest Enemies of the Universe)

During the New Dalek Paradigm's rule over the Sunlight Worlds, Jenibeth Blakely was captured by the Daleks at a young age and was kept as a prisoner for many years before being turned into a Dalek puppet. However, she was able to resist her conditioning because she still had the mind of a child. She attacked the Dalek Time Controller and destroyed some of its guards, forcing it to retreat. (PROSE: The Dalek Generation)

Puppets continued to be used by the Resurrected Dalek Empire. Threatened by the inmates of the Dalek Asylum planet, the Parliament of the Daleks sent Dalek puppets to capture the Eleventh Doctor and his companions for their help. (TV: Asylum of the Daleks) Assisted by a hooded figure, (WC: Asylum of the Daleks Prequel) the puppet Darla von Karlsen lured and captured the Doctor in the ruins of Skaro. On Earth in the 2010s, Amy Pond was acquired by Cassandra, her make-up artist turned puppet, whilst Rory Williams was acquired by a bus driver.

The air of the Dalek Asylum contained a nanocloud and so the conversion process occurred when any unprotected non-Dalek landed on the planet. All intact bodies of the Alaska had this fate befall them, apart from Oswin Oswald, who was entirely converted to a Dalek by the unhinged inmates. After Oswald removed the record of the Doctor from the Dalek pathweb, both the Daleks and their puppets lost their memory of him. (TV: Asylum of the Daleks)

During the Siege of Trenzalore, the Daleks attacked the Papal Mainframe and converted everyone into Dalek puppets, including the Silents. Tasha Lem, however, was able to resist her conditioning and destroyed three Daleks that threatened the Eleventh Doctor and Clara. Through converting Lem, the Daleks were able to remember the Doctor. (TV: The Time of the Doctor)

Bit by one of Colony Sarff's snakes, Bors was converted into a Dalek puppet and located the Twelfth Doctor's TARDIS for the Daleks in 1138. (TV: The Magician's Apprentice)

Behind the scenes
Many enemies in the Doctor Who: Legacy mobile game are Dalek puppets of allies or other enemies, including Silent, Tasha Lem and several Church members.