Garm Bel Iblis
Another Zahn creation, Garm Bel Iblis entered the scene in part two of the Thrawn Trilogy, Dark Force Rising (1992). In this book, we learned that Iblis played a major role in the formation of the Rebel Alliance, especially when it came to commanding a naval fleet.
Not until The Force Unleashed (Xbox 360/PS3/PC, 2008) did we see how that all unfolded. Convinced by Starkiller that an organized rebellion against the Empire was the only option, Bail Organa teamed with our playable antihero to gather the founders of the Alliance, which included himself, Bel Iblis and Mon Mothma. Did Bel Iblis do much more than that? Nah... he didn't even speak. It was cool to see him standing there, though, even if this meeting is only the stuff of "Legends."
You can also find Bel Iblis in Rebellion and Empire at War: Forces of Corruption if you ever get that feeling that you just need more Garm in your life.