Cyber-Lieutenant (Earthshock)

A Cyber-Lieutenant served under a Cyber-Leader on the Cybermen's plot to destroy the Earth to prevent an alliance forming to destroy the Cybermen. Based on a freighter, they planned to use a Cyber-bomb to destroy Earth. However, the bomb failed thanks to the Fifth Doctor.

After the bomb failed, the Cybermen began a second plan to destory Earth. They planned to reawaken an army of Cybermen in the freighter and take over the ship and crash it into Earth. The lieutenant was in charge of reawakening the rest of the Cybermen.

With the frieghter set to crash into Earth, the leader decided to use the Doctor's TARDIS to escape the ship, with the lieutenant accompanying him. While the lieutenant was searching the rest of the TARDIS, the Doctor destroyed the leader with Adric's gold badge. The lieutenant entered the control room, but Nyssa used the leader's gun to shoot and destroy the lieutenant before it could kill the Doctor. (TV: Earthshock)

Behind the scenes
this cyber-lieutanant is the first cyber-lieutenant to enter the TARDIS.