A person who would like to be different from how they are at present.
Typically, such persons would like to become famous, or admired by the world at large.
Often, they are aspiring pop vocalists or instrumentalists, or performing artistes of some kind.

People trying to hard to be cool (see tryhard)
Often pretending they know heaps about a certain subject when they don't.
In my opinion all the "Britney" fans and those boy bands, just coz they can't play Reeeeeeeel music.

many people are called wanabees but the biggest wanabees are people that dont accept other people and slag them off. These people that call other bands fakers or sell outs are the wanabees if they were normal they would just accept other music styles. They try hard to show other people that only the music they like is good and any other band is crap. No band is trying to be anything they're just doing what they do and most of them don't care if they're punk or goth or whatever. They just play what they believe in.These people wanabee cooler than others and so it is the people that enjoy the music and accept and appreciate other music that arent the wanabees, however much you call them that

Someone who sees someone cool and then wants to be exactly like them
or
a person trying to be goth/scene/emo whatever...
There are a numer of these people at my school. They are all thirteen, they all have sidepartings and they all love HIM and bullet for my valentine. They all have stupid pictures of themselves looking shocked and pathetic and they all slit their wrists because someone who isnt a wannabee totally pwns them. A wannabee usually goes to see one band in there life, and that band wil always be my chemical romance.