Can another name that isnt mine be third person because im writing a third person MLA essay?

Huh? If you're writing in the third person, that "person" doesn't have to have a name. It's just a narrative. You describe what happened. Or, do you mean, instead of something like, "I told Jennifer to take an umbrella because it was raining," you want to write, "Joe told Jennifer to take an umbrella because it was raining." Sure, in that case you could pick whatever name you want.