Director Irvin Kershner provided the voice of Darth Vader himself in the temporary mix of the film, before James Earl Jones recorded the final version.
Star Wars: The Empire Strikes Back (1980)
Last month, a video of Patton Oswalt completely improvising a filibuster on what the Star Wars sequel should be during shooting of an episode of Parks and Recreation was posted on YouTube. As Oswalt has admitted himself that “this was bound to happen”, an animated version of his amazing filibuster/pitch is now online with animation by Isaac Moores.
It’s pretty amazing and you should watch it now.