After reading that headline you'd be forgiven for asking which Darth Vader, well that's easy; the original.

DAVID PROWSE, the man who originally played the evil Lord Vader is 79! 

It was...1977 when David attended an audition for a film entitled Star Wars. The film was not considered to be a big thing at the time and the audition was held by director George Lucas. At the meeting, George offered David either the part of Chewbacca or Darth Vader. Instantly turning away the role of Chewbacca, David insisted he play the lead villain Darth Vader. George asked David why he wanted to play Vader and he replied "Everyone remembers the villain, George." - IMDB

And now, everyone remembers the man who played the Darth Vader!