Timothy Zhann is a fantastic writer, I can't recomend the Thrawn Trilogy enough. Hier to the Empire, Dark Force Rising, and Last Command, Read them you'll not regret it, some of the BEST SW Fiction out there...
Can't understand the appeal of thrawn? Ods are, without him, We would not have ANY SSC Star wars figures, or new hasbro figures. The Timothy Zhan novels were One of the things that Helped to re-invigorate the Star Wars Phenominon, amoong other things.
Thrawn is a non-human, and He holds a grand Admar's rank in the Imperial Navy. The rank of a grand Admaral is the highest an officer of the Imperial navy can attain. The Emperor himself Hated Non-humans. This alone speaks for What he was capable of.
Tharawn Was, simply put, the last great hope for the empire after Return of the jedi. A brilliant Stratgist, and a masterful tactician. He had a phenominal understanding of Psychology, and art. He was able to learn everything he needed to know about a culture by simply studying their artwork. from this,m he could devise a stratgey that would exploit psychological weakneeses inherent to the species, and bring an entier world to it's knees in hours, where other officers would take days, or even weeks of bombardment.
I'm not 100% clear on his backstory, but If I remeber correctly, He's an exile from his own species, the Chiss. He's got the personality of a Vulcan Serving the nazi's, And I think that had something to dso with his exile. Anywho, He's encountered by an imperial patroll out on some backwater, and the imperials decide to use him for sport. Using ewok-like traps and tricks, he holds off two squads of troopers for a week or so, killing them as he can. Eventualy Vader is called in to " deal with" the nuscance. The Emperor Requests that he be brought in alive, and thrawn is essentialy Pressganged into service. Like i said i'm not 100% on the accuracy of that, but That's what i understand of his history.
in the end, He is killed by his own bodyguard, a Victim of his own major character flaw, his overwhelming arragance.
Oh, did I forget to mention that he's also the creator of the Boba Fett Look-a-like Jodo Kast? A persona He used in his early days in the impire for infiltration, and deep cover work on Corelia, untill his cover is blown, and he abandons the persona, and the armor.