Doctor Number 18: The Second Doctor
The Second Doctor, as played by Patrick Troughton. This Doctor perhaps doesn’t have many interesting notes that can be added other than when the character regenerates into the Third Doctor.
Unlike most of the main Doctors on this list, we don’t actually see the moment that the Second Doctor becomes the Third Doctor. Instead, we see The Second Doctor being told by the Time Lords that they must change their appearance. This came at a time before the term regeneration was established, and it could be viewed that the Time Lords were executing the Doctor to force this change of appearance.
Alternatively, it could be considered that the Second Doctor didn’t regenerate and that the Third Doctor is an altered Second Doctor. Of course, the Third is always considered as the Third, although there is wiggle room here as this change of appearence hasn’t been shown on screen…at least not officially.
Doctor Number 18A: The Interim Doctor
There is a fan film called Devious, which has had a production that has run for 30 years between 1991 and 2021 which features a version of the Doctor which is supposed to bridge the gap between Patrick Troughton’s Second Doctor and Jon Pertwee’s Third. This is of note primarily for the reason that Jon Pertwee reprised his role of the Third Doctor in a scene filmed in the mid 1990s to show the hand off between the ‘Interim Doctor’ and the Third.
Footage from the fan film featuring Jon Pertwee was included in an official BBC DVD release and audio of Jon Pertwee as the Doctor from this recording was repurposed into an audio adventure as well. Marking Pertwee’s final performance as The Doctor, this story has significance, but has not ever been officially included to make the Interim Doctor, played by Tony Garner an official Doctor. Once the final episode of the series is released in 2022, it could bring new interest to the project and within time it could be included as official canon, and would mark the first time a fan project has entered the official timeline of the show.
Doctor Number 19: The Third Doctor
As covered above, Jon Pertwee did film unofficial footage showing him become The Doctor, but otherwise the first time we see the Third Doctor he falls unconscious from the Tardis and we don’t see how the change from the Second Doctor actually happened.
Other than this we do eventually see him regenerate into the Forth Doctor.
Doctor Number 20: The Forth Doctor
As covered earlier it is during the era of the Forth Doctor that we got the Brain of Morbius episode which showed us the faces of eight previous incarnations of the Doctor. This is perhaps the biggest point of note during the reign of the Forth Doctor and but there is one other version of the Doctor to muddy the waters just slightly, but we won’t give them a direct number. This other version is…
Doctor Number 20A: The Watcher
As a precursor to the Forth Doctor’s regeneration into the Fifth, the Forth Doctor saw a mysterious figure dressed all in white and with an unusual unformed face. The Forth Doctor seemed to have an understanding of who the Watcher was and knew that this figure would be involved in his regeneration. As the regeneration began it was acknowledged that the Watcher was the Doctor all along, although how this makes sense has never particularly clear.
Unlike other interim Doctors that bridge the gaps between regenerations on this list, The Watcher is unique in that they appeared before the actual regeneration began. In this sense the Watcher serves a similar function to the Ood warning the Tenth Doctor of his impending regeneration, or as has been seen more recently with Time warning the Thirteenth Doctor. It could be said that figures often get a sense of the Doctor’s impending regenerations, but why only the Forth got a version of themselves is unknown.
