No wonder the cast and crew are feeling a little emotional after its airing on Saturday night.
Michelle Gomez' Missy took her final bow alongside John Simm as the Master – and after the episode was full of praise for director Rachel Talalay.
No Mondasian Cyberman was going to get in the way of Talalay's fun.
Gomez called her time on Doctor Who "three wonderful, heady, marvellous years" – and lay down the gauntlet for her successor.
"Nobody will be able to match Missy," she said.
— Doctor Who Official (@bbcdoctorwho) July 1, 2017
Matt Lucas too celebrated "the best crew I have ever worked with" – apart from the people constantly following him around for these silly YouTube videos...
Showrunner Moffat too was in reflective mood as he sat down with the Doctor Who Fan Show to discuss the final episode.
Talking about companion Bill's possible fate, Moffat said he didn't believe she was "dead" – and wouldn't have wanted to finish his final series that way.
"I don't think Doctor Who is that kind of show. Doctor Who is a big-hearted, optimistic show that believes in kindness and love and that wisdom will triumph in the end," he said.
"I don't believe it's the kind of show that says there are bitter, twisted, nasty endings because it's not. It's not gritty – it's aspirational. It says, 'It can work. And wisdom and kindness will triumph. And love will always come through in the end.'
"I think there aren't enough people or enough shows saying that and I'm damned if Doctor Who is going to join in with the general chorus of despair. So, she doesn't die. She nearly dies and becomes something else.”
A worthy philosophy – here's to one more big-hearted Doctor Who finale this Christmas.