John "JNT" Nathan-Turner (born John Turner, 12 August 1947 1 May 2002) was the longest-running producer of Doctor Who, lasting from August 1980 to the end of the original series run in December 1989, overseeing the last season of Tom Baker and the entire tenures of Peter Davison, Colin Baker and Sylvester McCoy.
He got his start on the show in 1969 as part of the floor crew before ascending to production unit manager under Graham Williams in the late 1970s, and ran the show from season 18 (1980) through season 26 (1989). He was a strong proponent of using Continuity Porn, Stunt Casting, and giving his Doctors Limited Wardrobes of Impossibly Tacky Clothes, often as part of an effort to "brand" the programme.
His tenure as producer was very controversial for a number of reasons, mainly for the things listed above. He insisted upon a question mark motif being integrated onto the Doctor's wardrobe, which none of the actors playing the part were happy about. He was something of a Control Freak and unlike his predecessors wasn't particularly keen on bringing back previous writers or directors, instead preferring new inexperienced writers.
Nathan-Turner was also bit a too friendly with the fandom, which resulted in stories that suffered from Continuity Lockout, especially in era before home video or steaming (Jon Pertwee Era script editor Terrance Dicks believed that the audience should never be expected to remember details from an episode that was over two years old). His choice of guest stars was often criticized as they were often light entertainers terribly miscast in their roles. Despite this his first four years were generally well-received, particularly the show's 20th anniversary season in 1983 - something Turner had done quite a lot to promote. It wasn't until that Peter Davison decided to leave that things went horribly wrong.
For the Sixth Doctor - Colin Baker, John Nathan-Turner made very two important but very bad decisions; first he decided to make him a "totally tasteless Doctor" giving him an infamously gaudy multicolored coat that even the actor hated (Baker wanted his Doctor dressed in more tasteful black velvet). The second was he wanted the new incarnation to be a much darker chap than previous incarnations. It might've worked, for it not for two things. Rather than take the time to properly develop the Sixth Doctor with his own season, they tagged his debut story onto the end of Davison's last season as a ratings stunt — the result was disastrous as the new Doctor came off as arrogant, moody, and unlikable, especially given the now infamous scene where the Doctor, while suffering from post-regenerative psychosis, nearly strangled his own companion to death; the coat just made things worse. Second, Turner's insistence on hiring inexperienced writers came to haunt him as they had no idea how to write for the character, resulting in script editor Eric Saward having to extensively rewrite the scripts and his relationship with Turner quickly deteriorated; Saward (unfairly) thought Baker had been miscast and would often sideline the Doctor when he could.
The results were disastrous. Viewing figures took a nose-dive and the show was involuntarily put on a 18 month hiatus at the order of BBC1 Controller, Michael Grade (who hated the show and wanted it canned). Baker had another disastrous second season (Eric Saward had finally had enough and quit with one episode to go, causing utter chaos both on-screen and off) and he was fired as he was unfairly made the scapegoat for the show's problems (despite this he still loves Doctor Who dearly and was even made President of the Doctor Who Appreciation Society).
Turner, naturally had actually wanted to leave the show by this point, but he was forced to stay on as nobody else wanted the job; he mainly became concerned with just keeping things going, while new script editor Andrew Cartmel became the driving creative force for the classic run's last years. The show limped on for three more seasons before fizzling out; even though Cartmel was trying and succeeding to breathe new life into the show, the damage had been done, not helped by the BBC executives deliberately tanking the ratings by scheduling the series against ITV's flagship Prime Time Soap Coronation Street. It wouldn't be until 2005 that a new producer would bring the show back to massive popular and critical acclaim.
In later years, he was responsible for the direction of the home-video releases of Doctor Who, and produced some of the earliest of the show's bonus features in the form of short documentaries on specific Doctors and villains.
Always known for liking a drink, this ultimately developed into full-blown alcoholism, leading to his death at the age of 54 in 2002.