7. The Web of Fear - Episode 3
In the case of The Web of Fear, in some ways, we're extremely fortunate, as most of the story survives. Even more amazing is that this wasn't always the case - for an incredibly long time, only episode 1 existed in the BBC Archive. This changed in 2013, when it was announced that most of the remaining episodes had been found in Nigeria.
So in some ways, the fandom is extremely fortunate to have as much of The Web of Fear as it has. The only episode that's missing is episode 3. However, the missing episode is incredibly crucial. Not just for the serial, but for the whole of Doctor Who history. Because this is the episode that Colonel Lethbridge-Stewart - best known to fandom as the Brigadier - is introduced.
Considering how much of an incredible impact this single character has had on Doctor Who and the many Doctors they ended up meeting, it's hard to deny that the loss of this single episode feels very much like a crucial one.
Even worse is knowing that at one point, episode 3 had been found along with the other episodes. Unfortunately, in the months between the discovery of the episodes and their return to the BBC Archive in the UK, episode 3 had gone missing, likely stolen and sold to a private collector.
The idea that this episode came so close to returning to the BBC Archive, only to go missing once again for shockingly selfish reasons, is a massive shame. Perhaps one day, the episode will be given back to the BBC and fans will get to watch it again. But, even knowing that it still exists out there, it's a very small hope.