Sate Pestage was a long-time advisor to Palpatine, and one of the few people who truly knew him. Pestage was a staff aide to Palpatine when he was a Senator, and even before that when Palpatine was a minor functionary on Naboo.
After Palpatine was elected Supreme Chancellor of the Galactic Republic, Pestage controlled the executive agenda. He also covered up Palpatine's secret assassinations, and may have known Palpatine was Darth Sidious. During the hunt for Darth Sidious, Mace Windu suspected Pestage might actually have been Sidious, discounting Palpatine as he was Chancellor.
Shortly after the Empire's rise, he compiled a report on Order 66 for Palpatine. During the Great Jedi Purge, he fabricated numerous record giving the reasons for the Jedi executions, often accusing them of the very war crimes they were struggling to prevent.
Pestage eventually became Grand Vizier, his daily tasks ranging from managing Palpatine's schedule to tasting his food to see if it was poisoned. As time went on, Pestage gained more power.
By the Battle of Hoth, Pestage was actually running the Empire day to day. Only Emperor Palpatine and Darth Vader held more power than him. After Palpatine was killed at the Battle of Endor, he assumed control of Imperial Center until Ysanne Isard betrayed him by compelling him to leave the crucial trading planet Brentaal IV inadequately defended against the New Republic. , Isard sent Admiral Daala to kill Pestage
Anticipating Isard's betrayal, Pestage opened up talks with Princess Leia Organa detailing an offer to leave Imperial Center undefended in exchange for amnesty. Despite a rescue attempt by Rogue Squadron, Pestage was unwilling to be transported in the same shuttle as Ibtisam, a deceased Mon Calamari pilot. He subsequently evaded his own saviors and offered part of his vast wealth to Admiral Daala in exchange for his life. Daala, however, shot the crafty vizier in order to express his contempt for this sort of "weak" bargaining.
