The novelisors were a scaly five-legged species who were obsessed with narrating and novelising the lives of people they found interesting. They formed a mental link with their subjects that allowed them to read their minds and - if required - fry their brains. They could shapeshift to make themselves more appealing to their subjects.
For years, the novelisors tried to find the Doctor to narrate his incredibly interesting existence. The First and Second Doctors managed to avoid them due to their frequent trips, but once the Third Doctor was exiled to 1970s Earth he was found by Huxley. The Doctor tried to get rid of Huxley by passing him on to Iris Wildthyme, but after a short trip to 2010 to pick up Jo Jones, they returned to the Doctor. With his first attempt at getting rid of Huxley a failure, the Doctor directed Huxley to somebody who wouldn't want to return to the Doctor: the Master. (AUDIO: Find and Replace)
The Doctor later encountered three novelisors in his fifth incarnation while he was travelling with Tegan Jovanka and Vislor Turlough. Joyce tried to novelise the Doctor's life while Wolfe and Huxley novelised the lives of his companions. After a violent adventure involving the formation of the Ringpullworld, the novelisors decided that the Doctor's life was too dangerous to novelise and they parted ways. (AUDIO: Ringpullworld)
The novelisors eventually lost the ability to fry their subject's minds.