That is SUCH a fun question
& I can think of many I like but when it comes to what would I be... Probably the increasingly unsettling noises that freak everyone out but turn out to be something harmless (and distraction from the real horror that's about to happen)
If I had to pick a less harmless alternative, the obsessive stalker/creep getting away with gaslighting the main character for way too long in a psychological horror (wishful thinking; it's a roleplay/writing fav <3)

Tangentially, in middle school someone compared me to the stereotypical onryou/long dark haired jp ghost girl... That's off, but I felt honored at that time lmao.