David Prowse is the body actor of Darth Vader in the original trilogy. At six feet and five inches, the British bodybuilder towered over his co-stars. During A New Hope, Prowse thought that he was also the voice of the imposing villain. Carrie Fisher said in the documentary Empire of Dreams that Prowse’s voice was so banal that they would call him “Darth Farmer,” which makes it less surprising that George Lucas would choose to cast a separate actor to voice the intimidating Sith Lord.
After discovering that his voice had been replaced with that of James Earl Jones, Prowse was so frustrated that he stopped learning his lines for The Empire Strikes Back and Return of the Jedi. Instead, he would improvise lines, sometimes speaking complete gibberish, forcing his co-stars to respond as if he had said the correct line.