Season 7 Episode 1 - Day One of Twenty-Two Thousand, Give or Take
The heretics descended on Mystic Falls and the show proved that it could go on with Elena.
Season 3 Episode 22 - The Departed
Elena becomes a vampire... with Damon's blood in her system!
Season 1 Episode 22 - Founder's Day
"Hello John, goodbye John," said Katherine Pierce as she chopped John Gilbert's fingers off, giving viewers the moment they had been waiting all season long for.
Season 8 Episode 14 - It's Been a Hell of a Ride
Damon made the ultimate sacrifice, choosing himself to die over Elena and Stefan. It proved Damon was not as selfish as we had been led to believe. The episode also dropped the bomb that Katherine Pierce was the Queen of Hell after Stefan murdered Cade.
Season 4 Episode 18 - American Gothic
Elena and Rebekah joined forces to find Katherine, who had compelled an entire town to like her. Oh, she also had the cure and was hitting bone town with Elijah.
Season 3 Episode 5 - The Reckoning
Klaus returned to Mystic Falls for his pretty little doppelgänger. This also involved him compelling Stefan to feed on her. Yes, it was one of the best.