The Risen Empire  (English, Hardcover, Westerfeld Scott)

The undead Emperor has ruled his mighty interstellar empire of 80 human worlds for 1600 years. Because he can grant a form of eternal life-after-death, creating an elite known as the Risen, his power is absolute. He and his sister, the Child Empress, who is eternally a little girl, are worshipped as living gods. No one can touch them. No until the Rix, machine-augmented humans who worship planetary Al compound minds. The Rix are cool, relentless fanatics, and their only goal I to propagate such Als throughout the galaxy. They seek to end, by any means necessary, the Emperor's prolonged dynasty of one, and supplant it with an eternal cybernetic dynasty of their own. They begin by taking the Child Empress hostage. Captain Laurent Zai of the Imperial Frigate Lynx is charged with her rescue.