Rock Star developer is a legend about a guy you hire.
He is the one that closes all the issues so fast you can't believe it, writes clean code, writes the documentation, and then refactors some ugly piece of code on the other end of your app/site into something beautiful.
Every team member understands his code, yet don't know how to implement it, especially in that short time. He does code reviews, writes tests, finds ways to make your site/stack/app/build process better, faster, cheaper, safer. And he does all of that 10x faster than other devs. So when he's out of work, he writes blog posts and conference talks and everyone claps and follows him on twitter and sends him linked-in requests and knows your company because he works there.
In his free time, he contributes to open source, works on side projects and his github profile shows full green. You're probably using his libraries.
He's that creature of myth created by the internet that every PM wants to work with, every CTO wants on his team and every recruiter chases. The ever eluding white rabbit of development.
