Paxton Rall is supposed being a famous pirate. He is usually a brand new character added on the game, therefore we currently don’t know why or how famous he or she is exactly. This is how BioWare described him from the SWTOR Credits announcement:

This holiday, the Star Wars: The Old Republic team is excited to announce a brand new Premium player (Subscriber) reward – the newest Twi’lek Pirate Companion, Paxton Rall! The most notorious pirate to elevate to fame throughout the galaxy since invasion with the Eternal Empire, Paxton Rall scours the celebs in an endless search for SWTOR Credits US adventure and profit, making her a formidable ally as part of your Alliance.

The achievement involving Paxton I mentioned above is termed “Cantina Crawl” and it is earned by discovering Paxton in several Cantinas through the known Galaxy.