I’ll go first.
The Guardians in BOTW and those hands in TOTK.
Maybe it’s the music, maybe it’s the instant atmospheric change or just the fact that all I could think of doing the first time I encountered either was run in the other direction or well, die and start again from my last save.
Either way, it definitely changed the way I played this game after that, the exploration became a lot more cautious. At least until I learned how to perry and defeat them.
Felt like a real achievement.
I love games.