10 Great Characters Game Of Thrones Ruined
8. Arya Stark
Arya was one badass little she-wolf. Her natural distain for all things 'ladylike' set her up as an interesting character in a world of archaic gender roles. Sure, we had other strong female characters - Cersei and the Queen of Thorns weren't to be messed with - but they acted within the confines of a female role at court, scheming and plotting to get their ends rather than using outright force or action.
On the other side of the coin we had Brienne of Tarth and Yara Greyjoy, who it was clear were outliers in Westeros. Arya was another such character. Her story arc essentially showed her breaking off the shackles of a male dominated society, transitioning from a lady of court to a dominating force in her own right.
Given the plot swamp she fell into during her time in the House of the Undying, it was necessary to give her a significant role to play in the latter series... , but killing the Night King? Come on, that just came out of the blue. Nothing in the show had been building towards that moment. "Subverting exceptions" is one thing but throwing out seven seasons of foreshadowing for the sake of surprising people is just cheap.
Arya should have had some major role in the downfall of House Lannister, her whole story had been building to that. Hell, that's why she trained with the faceless men and kept referring to her 'kill list'.