For those who are new to the street art world, first thing you have to understand. Banksy is the main reason why this industry is commercialized. But if you wish to go down the origin do look at these :
1 - Blek Le Rat : http://the23rdlife.blogspot.com/2012/08/blek-le-rat.html
Banksy pretty much copy this guy.
2- King Robbo : http://the23rdlife.blogspot.com/2012/08/king-robbo.html
Banksy decided to go to war with this Graffiti King
Here is a documentary with Banksy and Mr. Brainwash...