Steamroller Man

From Tardis Wiki, the free Doctor Who reference

The Steamroller Man was a data-tool designed by Jean Fulton to delete corrupted coding from the scenario generator of Shadow-Space, ironing out bugs in its programming. Its name and form came from one of Sandra Jane Rimdelle's childhood books. The Dead Man attempted to use it to activate himself, but failed. It managed to return both Nyssa and Simon Valdac safely to their home dimension before the Fifth Doctor and Rimdelle trapped it in a feedback loop, destroying it. (AUDIO: Masquerade)