Myths(TodoDeku)

This is my first so if there are any errors I will be happy to take them and I only own my OCs and no one else from the BNHA fandom.(or the other characters that are gonna be in this)
This is a story where Izuku's parents abandon him for his "ugly" look. He is taken in by the pro hero Eraserhead and is raised by him. Eraserhead also known as Shota Aizawa is shocked that this boys parents abandoned him for having features of his quirk! What is his quirk exactly,you may ask? It will all be reveled in time! But here's a hint:
-- I'm always heard of or thought of once
No one knows if I exist
Just like no one knows
if the mad hatter eats cake or tea
I come in many versions
Many are harmful
Many are helpful
But none have been spotted
I am not one but many different beings
What am I?

This is not meant to rhyme but I couldn't think of anything and I won't be updating a lot but I will try my best to keep up! Spelling errors are expected. Should I try to make the riddle better? It's quite confusing! Even I must go through a maze to find this little haze of an answer!