What's a single word for a person who doesn't follow the crowd?

I'm looking for a word with a positive undertone to describe a teenager who does her own thing and doesn't cave in to peer pressure. Any suggestions? Thanks.

Question edited 1/30/16. Someone marked this question as a duplicate, but I think the other question is quite different from the one already posted. The other question is asking about a single word to describe someone who doesn't follow the crowd for the single purpose of being contrary. A contrary state of mind has nothing to do with what I'm looking for. I'm writing a recommendation for a teenager who is polite, independent, confident, and doesn't follow the crowd... NOT out of a sense of being different for the sake of being different, and not because she's ornery and contrary, but because she's her own person, and not swayed by what the other teens are doing. Can we re-open this discussion?

Solution 1:

In one word "independent", in two "independent minded".

Solution 2:

Consider Maverick:

A person who shows independence of thought and action, especially by refusing to adhere to the policies of a group to which he or she belongs. (TFD)

a person who refuses to follow the customs or rules of a group (M-W)

Solution 3:

lone wolf

a person who does not conform to generally accepted standards or customs

On the link, there are many good synonyms as well, including "counterculturist", and "individualist".