Lester

Bill Lester was a member of the Nerva Beacon crew. (AUDIO: Return of the Cybermen)

The Voga account
He, Commander Stevenson and Kellman were the last survivors of the plague affecting the station. When the Cybermen captured him, they forced him to carry Cyberbombs deep inside Voga on a suicide mission, but he was rescued and helped the Fourth Doctor defeat them. When the Doctor and Harry Sullivan were running away from some Cybermen, Lester sacrificed his life so that they could get away. When the Doctor's plan to suffocate their chest cavities by plugging them up with gold did not work and the Cybermen overpowered him and Harry, Lester leapt down from a rock ledge, catching the Cybermen by surprise. He immediately released his Cyberbomb harness, setting off a fail-safe in the event the bomb was detached from him before it reached the core of Voga. Instead of exploding at full power, a secondary explosion went off, killing the Cybermen, but also disintegrating him. (TV: Revenge of the Cybermen)

The asteroid account
According to another version of events, where the Cybermen sought to destroy a gold-rich asteroid, Lester never left Nerva. He was injured facing the Cyber-Leader but survived. (AUDIO: Return of the Cybermen)

Behind the scenes

 * The differing fates of Lester in Revenge of the Cybermen and Return of the Cybermen were originally accounted for in a post-credit scene written by John Dorney for the latter. As a result of the fallout of Genesis of the Daleks and the Last Great Time War, the Return timeline becomes redundant and is overwritten by the Revenge timeline. However, the scene was cut from the script and not included in the final product.