1. "Hold the door" – Game of Thrones
Episode: "The Door", Season 6, Episode 5
In a season filled with massive moments and big reveals, "hold the door" stands out for a couple of reasons. Like other scenes, it was beautifully executed and revealed something fans had speculated about for years (in this case, the origins of Hodor and his name). But it also explored the absolutely devastating effects of Bran's powers and the tragedy of Hodor's life. It was gut-wrenching to see Hodor sacrifice himself - or rather, Bran sacrifice Hodor - but also somewhat gratifying to have a much-beloved minor character be given a significant backstory and heroic ending.
2. "What door?" – Westworld
Episode: "Trompe L'oeil", Season 1, Episode 7
It's been a big year for doors on TV. When Bernard said those two words it confirmed what fans had been theorising about for half the season: that he was secretly a host, programmed so he couldn't see things that would confuse/upset him. The twist made us question everything we'd previously seen on the show and played into the larger themes about the nature of reality and what it means to be a person - human or otherwise.