Someone keeps calling me fat and ugly. It doesn't help that I'm insecure... what can I do to make them stop?

Don't listen to them they are jerks who think are better than others that happened to me before and stopped find people who love you for you and defend you that will make the haters think what they have done

Talk to the school counselor maybe? Or perhaps a parent?

HIT THE-
I mean, be responsible. If telling them to stop, ignoring them, or telling an adult doesn't work, try and get rev-
Try and stand up for yourself nicely.

@TinyOtaku ignore them bc i know how it feels when they call you fat and ugly they probably jealous that your pretty and not them tbh don't listen to them they are trying to make you life a hell but don't let them and if they don't listen use violence and threat them or in my case when they are older i'm might kill them... don't ask why oki..

What ever they say to you is not true...looks don't matter...but...what really matters the most...is from the inside is what makes you special...we all may be different...but deep down inside...we are more than that...it doesn't matter of what we are....it's who we are from the inside is what counts...?

Beat the crap out of them, I did that to a bitch who called me anorexic

You look great! I know my advice is gonna suck, but here goes:
Don't listen to them. They have no idea what they're saying. Tell an adult (your parents, a teacher, etc.)
And the most important thing I can tell you: don't do ANYTHING you'll regret. I say this because some kids resort to suicide or payback, which is not a good choice. You will regret it later. It might seem hard to you, but stay strong. Not all problems will last forever, and suicide is a permanent solution to a See More▼ temporary problem. It's not worth it.

Walk away. If they keep following you ether make it look like your not paying attention or just say "I know" even though I dought you that bad.