One who hovers on forums, blogs, post websites, etc. They are very well known on funnyjunk due to the fact that they can post many times in a few minutes. They spell the name wrong, not for irony, just to make the other people who spelt the word wrong feel dumber. Even if you post n00b, txt, or any other obscene way: They will correct you. They all co-encide under "one" leader, Grammar Hitler, but it's really just random people who say they're Grammar Hitler.
hell2one: That guy got PWND!
Grammer Nazi: It's Pwned you idiot