C is for... Cyber Controller

The leader of the Cyberman race, who was based on the planet Telos. This became the home of the Cybermen after their original homeworld of Mondas was destroyed. The Controller was distinguishable from the rest of his kind as he was taller, had no chest unit, and his helmet had a much larger cranium, with no side handles. The cranium case glowed, and the Controller's increased brain could be seen within it. Both helmet and body were of a darker hue than the other Cybermen.
As their resources were running low, the Controller had ordered that all Cybermen on the planet should put themselves into cryogenic suspension. He took up a position in a sealed chamber on his own, behind a large stylised relief of a Cyberman head. Their tomb complex was rigged with booby-traps, and the Controller hoped to convert any explorers who came looking for them.
Once reanimated by the Logician Eric Klieg, the Controller ordered the servant of Klieg's partner, Kaftan, to be partially converted, and deployed Cybermats to attack the archaeological expedition after they had escaped back to the upper levels and sealed off the tomb area. Klieg allowed the Controller to come up to the surface with the servant - Toberman - as he wanted to strike a deal with the Cybermen. The Controller first had to recharge himself, and an attempt to lock him in the recharge unit by the Doctor failed when he smashed his way out. He had mental control over Toberman and ordered him to attack Klieg, and then killed Kaftan when she shot at him. The Doctor used Toberman's previous loyalty towards his mistress to turn him against the Controller and he attacked him. The Doctor had the tombs evacuated and set about electrocuting the main doors. The Controller tried to break out, but Toberman closed the doors - forming the electrical circuit. This killed the servant, and apparently destroyed the Controller.

However, on the Doctor's subsequent visit to Telos, now in his sixth incarnation, he discovered that the Controller had survived. His body had been upgraded to a similar form as his underlings, but he was still taller and retained the larger cranium, without side handles to the helmet. He was working on a plan to prevent the destruction of Mondas using a captured time vessel. He knew of a plot to steal this but allowed the attempt to proceed as it would make for an interesting psychological experiment. The surface of Telos was also being mined with the highly volatile mineral vastial, as the Controller wanted to observe the destruction of the planet once they were ready to return to Mondas.
In Cyber Control, the mercenary Lytton, who had been in league with the Cryons - Telos' native species - stabbed the Controller in the arm, allowing the Doctor to then shoot and destroy him with a Cyberman weapon. Cyber Control was then blown up with a supply of vastial, along with the time vessel.

When a new race of Cybermen were created on a parallel Earth, their creator - industrialist John Lumic - was selected to become their Cyber Controller. He resisted conversion, wishing to remain human for a while longer, but his life support system was sabotaged by his lackey Mr Crane, and the Cybermen proceeded with the conversion to save his life. He was distinguishable from the other Cybermen by having an exposed brain case, glowing eyes, and a number of cables bolted to his torso, attaching him to his throne-like chair. When their emotional inhibitors were sabotaged, wrecking his Cyberman army, the Controller was unaffected. He was able to leave his chair, disconnecting the cables, in order to pursue the Doctor and his friends. They were fleeing in Lumic's own zeppelin, and the Controller began to climb up after them. Pete Tyler used the Doctor's sonic screwdriver to burn the rope ladder he was ascending, and he plummeted to his death in the exploding conversion factory.
A group of Cybermen who had been trapped for centuries in their crashed spaceship beneath the Essex town of Colchester attempted to create a new Controller by converting the Doctor's friend Craig Owens, but his love for his son allowed him to resist the process.

The Lumic Controller at the DW Experience in 2017.

Played by: Michael Kilgarriff and Paul Kasey. Voiced by Peter Hawkins, Michael Kilgarriff, Roger Lloyd-Pack. Appearances: Tomb of the Cybermen (1967), Attack of the Cybermen (1985), The Age of Steel (2006).

• Kilgarriff played the Controller in both of the two classic series appearances, though he was voiced by regular Cyberman vocal artist Hawkins in the first story. Regular monster performer Kasey was in the costume of the Controller in the 2006 story, whilst Lumic actor Lloyd-Pack provided the voice.