Grand Admiral Thrawn appears to be poised to become the next major villain in the Star Wars franchise, and the Legends continuity made Princess Leia invaluable to the Grand Admirals eventual defeat. Timothy Zahns 1991 novel Heir to the Empire, the first book in the beloved Thrawn trilogy, introduced Grand Admiral Thrawn as a new threat to the fledgling New Republic, and while Thrawn lacked Force powers like Darth Vader and Emperor Palpatine, he made up for it with sheer military genius. Thrawn was a particularly challenging adversary to the Star Wars original trilogy heroes, but he was not unbeatable.

https://screenrant.com/star-wars-legends-thrawn-leia-vital/