Tobias Vaughn was the managing director of International Electromatics, the world's leading electronics company.
Vaughn made contact with the Cybermen, formed an alliance with them, and then masterminded an invasion of Earth in return for a share of the power. (TV: The Invasion) Vaughn was semi-converted into a Cyberman; all the modifications were physical and his mind remained untouched.
However, Vaughn's plans for domination fell apart when the Cybermen thought he betrayed them. Allying himself with the Second Doctor (while using an invention that induced extra-strong emotions deadly to Cybermen), he helped the Doctor to defeat them. He was killed on a rooftop after being shot by a Cyberman. (TV: The Invasion)
At the moment of death, Vaughn's consciousness was transmitted via satellite into one of fourteen identical robot copies of himself. (PROSE: Original Sin) He infiltrated Department C19 through his old employee Martyn Townsend, and began influencing its operations. As Townsend's superior, Vaughn effectively controlled C19's "darker side" and the Vault during this time. He had Townsend organise the capture of a Silurian, intending to use its DNA to create a superhuman army. This plan was foiled by the Third Doctor and UNIT, who remained unaware of Vaughn's involvement. (PROSE: The Scales of Injustice)
Some years after the invasion, a film based on its events was shot by Lloyd Kingsley-Sayle. The role of Tobias Vaughn was played by an actor named Michael. The Second Doctor, using the public's ignorance of the Cybermen to his advantage, changed the name of the alien invaders to the fictional Zexians while also adding that Vaughn had a troubled childhood, explaining his motivation for helping the aliens. (PROSE: Scientific Adviser)
Over the centuries, Vaughn influenced and manipulated humanity's development. He invested the remains of International Electromatics' empire into new technologies, such as the BOSS supercomputer, the development of the Time Scoop, and Professor Kettlewell's inventions. As the Cybermen repeatedly attempted to invade Earth, Vaughn bought pieces of their technology in order to repair his failing body with what was left of his money.
In the 30th century, Vaughn encountered the Seventh Doctor. Vaughn captured the Doctor, hoping to learn the secret of time travel from him. The Doctor trapped Vaughn in the TARDIS, preventing him from transferring his consciousness to another body. The Doctor later removed Vaughn's brain crystal and installed it in Chris Cwej's mother's food irradiator. (PROSE: Original Sin)
Behind the scenes
- Likely due to copyright issues, Vaughn is never identified explicitly by name in the audio adaptation of Original Sin, although the dialogue between the unnamed villain and the Doctor makes it clear that the enemy is still intended to be Vaughn. Although not stating in which story, Nicholas Briggs mentioned his voice performance of Tobias Vaughn. (BFX: The Eighth Doctor: Time War: Volume Two)