Darth Vader is a character from Star Wars and was an enemy towards Sonic in Sonic for Hire. He is the main antagonist of The War story arc (consisting of the episodes "The War: Part One" and "The War: Part Two") and one of the three main antagonists of Season 3 (along with Shredder and Tails).
He is killed in The War: Part Two when Dominique Wilkins grabbed and dropped him into the Family Feud core reactor. His ghost returns in the end of the episode when Sonic and the gang celebrate their victory, along with the ghosts of Mario and Louie Anderson.
When Darth Vader was thrown into the Family Feud core reactor, it was the same as when Darth Vader teamed up with Luke and threw Emperor Palpatine in the death star's core reactor in Star Wars VI. This was a Star Wars parody