Doctor Who has managed to do what many shows haven't. It's kept itself fresh every time a Doctor regenerates and passes the baton to the next one. With hundreds of episodes and specials, the BBC show has managed to bring the audience some of the best sci-fi stories in TV history, reaffirming Doctor Who's legacy within the genre. But not everything is a success, as fans of the show will know, and not even Doctor Who is infallible.
Source:https://www.cbr.com/doctor-who-unpopular-episodes-ranked/