My parents finding my journal. Or my stash of money I saved.
Monster chasing me upstairs/downstairs! I’m not paranoid about it anymore, but I still run up and down stairs because of it
Mirrors.
Mascot costumes, I remember hiding under a table at the hometown buffet because they had giant bee mascot for some reason
I loved my cats so much as a little kid that I honestly believed that if someone broke into our house that they would try to hurt our kitties on top of trying to steal things.
I had no concept that a burglar really isn’t interested in pets but rather are only focused on valuables. I just thought people who broke into places they shouldn’t were generally evil and would do as many evil things as they could once inside, such as hurt my animals.
I am SUPER sensitive to pet or animal abuse as an adult now.