Darth Vader IS a Sith Lord hence why he is sometimes called 'Lord Vader'. Whether another Sith Lord is stronger than him is completely debatable.
Darth Vader
Definitely Darth Vader
Darth Vader
Darth Vader
Definitely Darth Vader
dark vader is.
Darth Vader
darth vader
Darth Vader
britney spears= 92.9% more famous than darth vader,
Darth Vader
Darth Vader