The Academy of Motion Picture Arts and Sciences nominates people for their specific contributions to specific films in a number of disciplines and crafts. Those people are in the credits of the films -except when they aren't. Sometimes the names the Academy has available really had nothing to do with the motion picture, or they aren't even real people. That doesn't stop them from getting nominated.
Roderick Jaynes is a pretty talented guy for not being a real person. Jaynes has edited all of the Coen Brothers movies and was even nominated as one of Entertainment Weekly’s Smartest People in Hollywood in 2007. Joel Coen explained that Jaynes probably wouldn't be making an appearance at the 2008 Oscars, despite the nomination. “He’s very old—late 80s, early 90s—so I don’t know if he’d make the trip." In actuality, the Coen Brothers edit all of their own movies and use the elderly Brit as a front. Jaynes didn't win for No Country, and when asked how the awardless editor was dealing with the loss, Ethan Coen replied, "We know he's elderly and unhappy, so probably not well."
Some of the other non-existent people in this list have sadder stories, and there's one that exists, but is a dog. Real all those stories at mental_floss. Link