Roboman

Robomen were humans converted by the Daleks into wholly-obedient slaves during the 22nd century Dalek invasion of Earth. These surgically-modified captives were used for patrols and overseeing other slaves. The so-called "Robomen" were needed because there were relatively few Daleks on Earth.

The Daleks captured prisoners and operated on their brain in a surgical procedure called the Transfer, plus fitting them with large helmet-like headsets. The mind control technique the Daleks used was unstable, and the Robomen would eventually go insane and commit suicide. (DW: The Dalek Invasion of Earth)

A more sophisticated implantation technique was revealed after the conquest of Vega VI. Rather than the Daleks fitting their subjects with grafted positronic discs and communication devices, the circuitry was placed inside the brain itself and the Robomen retained independent thought. Due to this, they were much harder to detect and considered far more dangerous. Orders from their Dalek masters would be filtered within normal thought processes, the subject seemingly unaware of the disc implant. One such Roboman was Gordon Pellan, who was gunned down by Earth Alliance forces. (BFDE: The Human Factor)

Mirana, another one of these newer, more sophisticated Robomen, was linked directly to the Dalek Emperor's mind. Mirana herself was unaware of the linkage, as demonstrated by her confusion when she was told of the implant. The implant itself is deemed impossible to remove without killing the subject, however it could be disabled. Mirana's implant was disabled surgically, though she was still able to receive transmissions from the Dalek command net. This was used by the remnants of the Earth Alliance to track a small battalion of Dalek forces on Lopra Minor. (BFDE: Project Infinity)