Umm... I suppose the thing I'm best known for is pretty stereotypically nerdy; The Guy who never goes out.
It's not really in a bad way, but whenever I run into my friends they're always saying "Dude, you never come out, you should come out!" or something similar. Of course there's an element of truth to it, I haven't hung out with friends in literally months, but I don't regard it as being viewed negatively, I'm just kind of a loner.
I wish I could be best known for something a little better though, like "the guy who will always help you out", since I'm hardly ever going to say no to something who's asking a favour, but no-one asks me favours, so I don't see that title appearing any time soon.