As it is impossible to get into every Thrawn-adjacent arc without coming across continuity issues, let’s keep things precise, yet brief. Also known as Mitth’raw’nuruodo, Thrawn used his encyclopedic knowledge about various cultures to his advantage, which helped birth strategies that targeted the group’s weaknesses. Known to have been exiled from his homeworld, it is later revealed that this backstory was but a clever ruse to confuse opponents and gain the upper hand when one least expected it. Thrawn’s fake backstory allowed him to gain importance amongst the ranks of the Empire pretty quickly, to the point he soon became an asset for Emperor Palpatine.
It is worth noting that Thrawn also crossed paths with Anakin Skywalker at some point, and the details of this unlikely dynamic are revealed in “Thrawn: Alliances” in a Clone Wars-adjacent flashback, where Thrawn offers Anakin help on a mission in Batuu after Padmé goes missing. Thrawn introduced himself to Anakin as Commander instead of Senior Captain to appear less intimidating and reminded him that victory was the goal, not revenge.
Thrawn’s rise among the Imperial ranks, however, was not easy, as he had to face discrimination due to his alien physiognomy. He befriended Eli Vanto at the Imperial Academy soon after, and the two worked closely together to resolve several cases, and Thrawn was promoted to Commodore within a short period, given his impressive track record. While his duties included crushing enemies of the Empire, he also dealt with the Grysk Hegemony, who threatened his homeworld at the time. Interestingly, Zahn originally kept Thrawn’s arc short and sweet by effectively killing him by the end of the “Heir to the Empire” trilogy. However, the character’s popularity led the author to write four more books, along with a tie-in prequel about Thrawn’s pre-Imperial days.