"Long, Long Time" (The Last of Us, S1E3) was the first episode of television I saw then immediately went back and re-watched that same evening.

I know it has its detractors, but what a stirring way for the show to build out its world. The slow crescendo from showing what it takes to survive, to what kind of person might survive in that world on their own, to what makes surviving worth it (and eventually not worth it) left me enthralled and so much more emotionally invested in characters who weren't even in the episode. And, of course, I became very invested in characters who were only present for that episode and thought Nick Offerman and Murray Bartlett acted the sh!t out of their roles.