Maybe even until now.
Undin from Shake, Rattle, and Roll III.
Undin is basically a slimy, frog-like monster/creature who plotted revenge on vacationers who took her eggs at the beach. She followed them back to the city through the sewers, climbing out of toilet bowls to kill those who kidnapped her precious babies. It was so scary that people who saw that movie may or may not have skipped their trips to the toilet for days. If you really think about it though, Undin was only doing what a loving mother would do. ¯\_(ツ)_/¯
Regal Films
Halimaw sa banga from Halimaw.
The story goes like this: An ancient witch gets trapped and killed in an antique jar. The witch turned into a monster after her death and, now, she kills anyone who looks into the jar. It's the reason why I don't look inside antique jars to this day.
NCV Productions
Lilia Cuntapay from Shake, Rattle, and Roll III (and literally anytime she plays as a white lady).
When you say "white lady," 90's kids would only think of one person: Lilia Cuntapay (may she rest in peace). She was the biggest ~KWEEN~ of white lady roles that, even though she's not playing one anymore, people still get a little creeped out.
Regal Films
The police, when you don't want to sleep in the afternoon.
Our parents told us that if we didn't sleep (especially in the afternoon), the police would come and get us because, apparently, it's a legal offense. And WE BELIEVED THAT SHIT. Who knows, maybe this is why we still feel anxious around police officers even though we're not guilty of anything. *cough*
Anvil Publishing / Inquirer