How to make an OC and NOT Mary Sue

Looks

Do NOT rip off an already existing character.

For example, if you're making a warrior cats OC, try not to make it look like a canon cat, if it's a creepypasta OC, don't take too many aspects from canon characters, you get the idea. One little aspect is fine. More than that could ruin the character.

Creepypasta OCs, please make it something practical. DO NOT make your OC wear a tight skirt or dress. How will they even run like that? Loose-fitted clothing will be better. Although, leggings are fine, just try to make the clothes practical.

As for other things, DO NOT RIP OFF JEFF THE KILLER!! I'VE SEEN WAY TOO MANY OCS LIKE THAT!!

Seriously, creativity, people! My OC, Purring Dentist, wears a blue surgical mask and a pale gray dentist coat with rips in it. No ripoff there!

Warriors OCs, I am sick of seeing gray cats! Warriors already has a bunch of gray cats! As for blue eyes, they're super overused! It's fine to have one or two OCs like this, but don't make ALL of them like this!

Disabilities, DO NOT rip off a canon cat! Things like Brightheart's face is overused, so is Cinderpelt's leg, Briarlight's injury, and same with being blind or deaf.

Kittypets, PLEASE, not one like Firestar! Don't make them run away just because they wanted to explore! Make a good reason for them to, or just don't make them a "full-on" kittypet! (What I mean by that is, maybe a therapy cat, a pet store cat, or a shelter cat)

And PLEASE DO NOT MAKE AN OC THAT'S A TWOLEG!! Can WE understand cats? No? Neither can twolegs from Warriors! If you do make a twoleg OC, please have a good reason for it! Maybe it's because of a prophecy! Don't make the cats trust the twoleg just because!

A dog OC is fine as long as you make a good reason for the cats to trust them. Don't make the cats trust the dog just because. Maybe the dog saved them from twolegs, maybe the dog gave the medicine cat herbs, CREATIVITY, PEOPLE!!

Undertale OCs, if it's a monster, don't make it the same as canon characters! Don't make it a goat-like monster! We already have Toriel, Asgore, and Asriel! Don't make it a skeleton! We already have Sans and Papyrus! Once again, CREATIVITY, PEOPLE!!

Human OCs are fine, just make them different from Frisk and Chara! Don't make anything similar to those two, otherwise it'll be seen as a ripoff.

And PLEASE, NO DOG-LIKE MONSTERS OR ACTUAL DOGS!! How many can I list, Dogaressa, Dogamy, Annoying Dog, Lesser Dog, and Greater Dog just to name a few! There's already so many canon ones!

Cats are a bit less used, the only ones I can really think of are Temmie, Catty, and Burgerpants. If you do make a cat-like OC, just make a good backstory to balance it out.

And for the love of hell, PLEASE don't make ANY OCs, no matter what fandom, recolors of existing characters! I can't think of anything more annoying and lazy than that! No recolors!