The Starmen by Leigh Brackett

The Starmen follows the adventures of Matt Carse, a hard-drinking adventurer and thief, and Princess Aladoree, the daughter of the deposed ruler of a distant planet. Aladoree is seeking the aid of a legendary race of powerful beings known as the Star Men to help her reclaim her throne from Ciaran.

Matt and Aladoree embark on a dangerous journey through space, encountering various alien races and facing many obstacles along the way. As they get closer to their destination, they must navigate treacherous political intrigue and personal betrayals. In the end, they discover the true nature of the Star Men ... and must make a choice that will determine the fate of the universe!