No episode has shown the 8th Doctor's regeneration. He was never in any series of the show, he was in the American made TV movie and in that movie they showed the 7th Doctor regnerate into the 8th, but we don't get to see the 8th regenerate into the 9th Doctor. It goes from the movie, to the revamp in 2005 with the episod Rose where the assumption seems to be that the 9th Doctor is fairly new and possibly recently regenerated.
The Eighth Doctor regenerated in the TV movie "Doctor Who: The Night of the Doctor". It is a special episode that aired in 2013, leading up to the 50th anniversary special.
Because it was a one off made for television movie.
the 50th anniversary special
Peter Kay was in the episode Love & Monsters.
In 1963, with the first episode being An Unearthly Child.
The first episode was aired on 23 November 1963. Recently there was a special episode to celebrate 50 years of Doctor Who.
It is unknown, the Eighth Doctor only appeared in a movie.
The eighth Doctor regenerated offscreen and nothing is known about how or why he regenerated. The eighth Doctor appeared onscreen only once in a TV movie. We know th Time War happened between the TV movie and the start of the 2005 series. It's widely assumed that whatever the Doctor did to end the Time War caused him to regenerate.
There is no episode with the eighth Doctor regenerating, he was only in the 1996 movie, and when the show returned in 2005 it was with the ninth Doctor.
NuWho -- Episode name : Utopua/The Sound of Drums/Last of the Time Lords. This is when we see Derek Jacobi regenerate into John Simm
29 October 1966. He got old in the last episode of "The Tenth Planet" with the Cybermen.
Ell even dies but he doesn't regenerate he regenerates in the last episode in the 5 series
Because it was a one off made for television movie.
Series 1; Episode 13 The Doctor (Christopher Ecclestone) had just saved Rose's life by absorbing the time vortex from her. He needed to regenerate and did so into Doctor number 10 (David Tennant). This happened right at the end of the episode, at the end of the first series.
Eighth Doctor was created in 1996.
He will regenerate into the 12th Doctor.
He'll regenerate into the 13th Doctor.
The Eighth Doctor regenerates in the 2013 short 'Night of the Doctor' special, between episode 13 of season 7, 'The Name of the Doctor', and the 50th anniversairy episode, 'Day of the Doctor'. He is killed in a spacecraft crash, but the Sisters of Karn briefly revive him and persuade him to modify his regeneration. So instead of directly becoming the 9th, he adopts a new persona, in between the two. The Seventh Doctors Regeneration WAS SEEN on screen, in the 1996 TV Movie (He clearly regenerates into the Eighth Doctor, played by Paul McGann). The Eighth Doctors Regeneration was NOT seen, and like the the original answer here says, it's widely believed that this transformation towards the end of The Time War. The Ninth Doctor (Christopher Eccleston) is surprised and amused by his apparant-new face during the first New-Series episode 'Rose' from 2005.