Chief Caretaker

The Chief Caretaker was the leader of Caretakers in Paradise Towers. Before he was made Chief Caretaker, he had been a renowned architect named Jax.

Biography
Jax was a renowned architect on his world who was brought onto the committee overseeing the construction of Paradise Towers. He had opposed the Chairman and the Liaison Officer when they proposed drugging the residents of the Towers with trank, a drug that would make them submissive. He attempted to plant a mechanism in the trank tank to allow him to shut down the machine once construction checks were finished. However, he was apprehended by the Liaison Officer and fell into the tank, absorbing lots of trank in the process. The Liaison Officer, knowing he would now be submissive due to the trank he ingested, believed Jax was the ideal candidate for the Chief Caretaker role at Paradise Towers. (PROSE: Trank Tank)

Unknown to his staff, the Chief had found a creature in the basement and made it his pet. He had the cleaners take it the bodies of the dead, believing that it ate them. The Chief even had Caretaker 345/12, subsection 3 killed to feed the creature. He thought of himself as the creature's "daddy".

When the Seventh Doctor was brought to him, the Chief thought he was the "Great Architect" — namely Kroagnon, who designed Paradise Towers. He ordered his execution and was called away after a report on the death of 345/12, subsection 3 came in. When the Chief returned, he found the Doctor had escaped and blamed the Deputy Chief Caretaker, who was tasked with his re-capture.

The Doctor was again brought before the Chief, who began interrogating him. He soon learned the Doctor was not the "Great Architect" as he had thought, but still ordered his execution. Once again, the Chief was called away after a report on the death of Tilda and Tabby came in. He went to the scene of the death and bribed Maddy by offering her the flat in return for her silence on the matter.

While making his way back to control, the Chief met with Cleaner 479, who forced him down to the basement. There, he was brought before the creature, who revealed itself as Kroagnon and needed a body to escape from his imprisonment. The Chief was forced into a container and corporelectroscopy was performed to transplant Kroagnon's mind into the Chief, effectively killing him. (TV: Paradise Towers)

Other references

 * In the video game Happy Deathday, played by Izzy Sinclair on the Time-Space Visualiser, the Chief Caretaker was among a host of "every single enemy" that the Doctor had ever defeated, who were assembled by the Beige Guardian and pitted against the Doctor's first eight incarnations. (COMIC: Happy Deathday)

Behind the scenes
Ronald Lacey, T. P. McKenna, Denis Quilley and Ian Richardson were considered for the role before Richard Briers was cast.