This goes for ALL OCs, no matter the fandom. DO NOT RIP OFF AN ALREADY EXISTING NAME!!
For example, creepypasta, I've seen too many people name their character and just put "The Killer" at the end! That's just lazy! We have two killers already! (Not counting Nina)
As for Warriors, I've seen people just straight up steal a full name! Sure, some names are bound to be similar, but I've seen someone call their OC Graywing, which is LITERALLY the name of a canon cat! Be more creative! It's fine to have the same prefix or suffix, but taking a full name is crossing the line for me!
I have an OC named Applefrost, but the only reason she has that name because I didn't know it already existed at the time. If you didn't know that name already existed in canon, that's fine, but if you KNOW the name exists, DO NOT use the name!
I've never seen anyone rip off a name for an Undertale OC, which is good! Keep it up!
In general, don't rip off names! Don't be lazy with names! Be as creative as possible!

YOU ARE READING
How to make an OC and NOT Mary Sue
RandomDisclaimer: Keep in mind that this is just MY opinions. If you disagree, that's okay. You're completely entitled to your own opinion. The title is pretty self explanatory. Just know, I am NOT a complete expert. I feel as if some of my OCs are Mary S...