The K1 Robot

An experimental robot, built by Professor Kettlewell, and designed for operations such as deep mining that humans could not cope with. The robot's programming was, however, meddled with, apparently under the auspices of Hilda Winters, director of Think Tank, Kettlewell's former employers.

The robot was used to commit murder when it was programmed to steal the destructor codes for a group of atomic missiles, as well as the components for a large disintegrator gun. Kettlewell, worried that the robot's artificial intelligence would be driven mad by the tampering, alerted Sarah Jane Smith, who struck up a rapport with the robot.

Kettlewell however, was actually behind the robot's reprogramming, determined to force the rest of the world to disarm by threatening them with the nuclear missiles. The robot accidentally killed Kettlewell and so opted to carry out his plan and fire the missiles. The robot was shot by Brigadier Lethbridge-Stewart using a disintegrator gun, but that simply caused its unique living alloy to expand, increasing its size.

The Doctor discovered that Kettlewell had also invented a virus to destroy the living metal and coated the now giant-sized robot in this. Slowly, the alloy was rusted away, until the robot was nothing but dust.