Daniel Hopkins

Daniel Hopkins was a UNIT medical officer from the 1980s. He assissted the Fifth Doctor in investigating the Helliax and Annabel Mordon. He turned down a request to travel with the Doctor due to the oncoming birth of his child. (AUDIO: The Helliax Rift)

A few years later, Hopkins' family was killed in an accidental house fire, an event which drove him mad with grief. To this end, he betrayed UNIT and became a sleeper agent for the Cybermen. When the Doctor returned in his sixth incarnation to aid UNIT in investigating the Cybermen's plot, he killed Lt-Col. Lewis Price and brought the Doctor to the Cyber Leader. He was partially converted into a Cyberman himself. In spite of his betrayal, the Doctor saved him from the Cybermen's destruction, but warned Captain Weaver to place Hopkins in secure containment and to be incredible vigilant should he ever recover. (AUDIO: Hour of the Cybermen)