Grand Admiral Thrawn
Arguably the most popular Star Wars character never to be so much as referenced in a movie, Grand Admiral Thrawn led an Imperial resurgence five years after the Battle of Endor beginning in Timothy Zahn's landmark novel, Heir to the Empire. Just three years after the book's 1991 release, LucasArts included Thrawn as a major character in its own space dogfighting classic, TIE Fighter for PC. As they fought Rebel scum from the Empire's perspective for the first time, players were treated to seeing Thrawn's rise from Vice Admiral to Grand Admiral throughout the course of the game, which was set between Episodes V and VI.
Only in the last few weeks has this story been incontrovertibly nullified, as Timothy Zahn's new novel, Star Wars: Thrawn, covers the same territory in the new canon. And as viewers of Star Wars Rebels know, he's officially Grand Admiral Thrawn long before the events of TIE Fighter, which would be far from the only LucasArts game to include him. Later Star Wars titles that include a dose of Thrawn include Rebellion (PC, 1998), Galaxies (PC, 2002) and Battlefront: Renegade Squadron (PSP, 2007).