Nicholas Bridgeman

 was a professor who was part of a ghost-hunting group. The Second Doctor, Ben and Polly met the group at the Grange, a haunted house they were investigating. Godwanna kidnapped him and while trying to unleash his psychic potential so he could activate the Euterpian beacon, severely damaged his mind. Wilding was later able to not only restore Bridgeman's mind, but to heal other psychological problems he had. He travelled back in time in the TARDIS and helped rescue his students before an explosion destroyed the Grange where they were trapped. (PROSE: Invasion of the Cat-People)