Psion
Adventurer
To me a munchkin is a powergamer who uses their power for evil.
A good powergamer will pay attention to the setting continuity, will identify things they know are overpowered to the GM before taking them, and will help other players optimize their character and make for a competent party.
A munchkin ignores setting logic or consistency, cares not if they hog the spotlight, tries to sneak in obviously abusive combos and the GM (and refuses to acknowledge there is anything wrong with them.) A munchkin typically couldn't care less if there are other players at the table.
A good powergamer will pay attention to the setting continuity, will identify things they know are overpowered to the GM before taking them, and will help other players optimize their character and make for a competent party.
A munchkin ignores setting logic or consistency, cares not if they hog the spotlight, tries to sneak in obviously abusive combos and the GM (and refuses to acknowledge there is anything wrong with them.) A munchkin typically couldn't care less if there are other players at the table.