Darth Vader in known through out the galaxy. He has tracked down and killed any Jedi that survived order 66. He is the leader of the galactic empire and leads the 501st legion himself. Vader has many leaders for the Empire. This is how Vader spread fear into the galaxy. only the remaining Jedi are the only ones who can stand up to him in battle. ( This Vader is if he would have taken another path during the clone wars and this changed the future from what we seen in the movies.)