10 Doctor Who Stories With WORSE Endings Than Flux
2. The Armageddon Factor (1979)
The Doctor has been tasked with assembling the pieces of the Key to Time, an ancient artefact that maintains the equilibrium of time itself. After defeating the Black Guardian on the planet Atrios, he's located the final piece.
The Key to Time was the umbrella theme for Doctor Who's fifteenth season, a quest narrative that would see the Doctor, K9 and new companion Romana travel through time and space locating each of the six fragments. Over six stories and twenty six episodes, they finally assembled this great artefact at the behest of the White Guardian.
And then, after a brief wobbly where he considers what it would be like to have unimaginable power over all of the universe - Timelord Victorious much? - he snaps out of it and prepares to hand it back to the Guardian. That is, until he discovers that it is not the White Guardian, but the evil Black Guardian in disguise. The Doctor breaks the Key up and scatters it back out across the universe.
Whilst there's something quintessentially Doctorish about him smashing up the very thing that gives balance to the universe, it does render the fifteenth series' central arc utterly pointless.