Darth Vader breathes really loudly. There's no reason for it, but for some reason it's scary as hell. That nightmarish mechanical sound follows him everywhere. That sound, and countless other little touches, were created by Ben Burtt. He has the boring job title of "sound designer," but he brought Star Wars to life in countless ways. (Trivia: Darth Vader's breathing is Burtt breathing through a scuba regulator.)
Ability to force-choke not included.
The high-pitched sound the blasters make? Burtt came up with that. Chewbacca's voice? Burtt created it by recording a moaning walrus and layering it with some other animal sounds. On top of this, he didn't just design R2-D2's sounds but actually performed most of them himself. That's right -- he is R2-D2.
But his work didn't stop with Star Wars. He also personally designed E.T.'s voice and personally performed the adorable voice of WALL-E. Yeah, he's WALL-E as well.