Palpatine was born on the planet Naboo and was secretly trained as a Sith Lord by Darth Plagueis before he killed him as part of the Rule of Two. After many years of training he went undercover as the senator of Naboo, and at some point took a young Dathomirian Zabrak as an apprentice, naming him Darth Maul. He eventually was elected for role of Chancellor of the Galactic Republic and the leader of the Galactic Senate. After Maul was defeated by Obi-Wan Kenobi, he took Count Dooku, a former Jedi Master, as his second apprentice. Dooku became the political leader of the Confederacy of Independent Systems in the Clone Wars against the Galactic Republic.
Still secretly a Sith Lord, Palpatine was plotting the Republic and the Jedi's downfall. He ended up turning Jedi Knight Anakin Skywalker to the Dark Side and becoming his master, giving him the title Darth Vader. Palpatine initiated Order 66 on the clone armies, ordering the clones to kill all of the Jedi, destroying the Jedi Order and forming the Galactic Empire. Palpatine then became the Emperor of the galaxy and ruler of the Empire along with his new apprentice.
During Empire Day an image of the Emperor was displayed on the HoloNet News on Lothal at Old Jho's Pit Stop presiding in the Imperial Senate on Coruscant the end of the Clone Wars and rise of the Empire with his Royal Guards. Governor Arihnda Pryce of Lothal was also invited to celebrate with the Emperor on Coruscant.
The Siege of Lothal
Sidious contacted Vader to ask if he had taken care of rebels. Vader informed him that they had been broken and that Anakin Skywalker's former apprentice, Ahsoka Tano was with them. Seeing this as an opportunity to locate more surviving Jedi, such as Obi Wan, he ordered Vader to dispatch another Inquisitor to hunt the rebels down.
Wolves and a Door
Following the Empire’s discovery of the Jedi temple on Lothal, Sidious became obsessed with unlocking its secrets. He ordered the excavation of the temple when he learned that it granted access to the “world between worlds”, which he could use to alter the events of time.
A World Between Worlds
After Ezra was able to enter the world between worlds, he saw a portal that showed Ahsoka’s duel with Vader on Malachor. He put his hand through the portal and drag Ahsoka out just as Vader was about to kill her. Sidious then used ancient Sith alchemy to open a portal into the world, believing Ezra and Ahsoka to be the key to entering the realm. He attempted to kill Ezra, who was saved by Ahsoka. Ahsoka returned to Malachor in the same timeframe as her fight with Vader, while Ezra escaped back to Lothal. He then used the mural of the Mortis gods on the temple to destroy the temple and kill Veris Hydan, who the Emperor had sent to oversee the excavation.
Family Reunion - and Farewell
After Ezra surrendered to Thrawn to prevent him from bombarding Lothal and killing its inhabitants, Thrawn took him aboard the Chimaera, where Ezra was brought before the Emperor in holographic form. Sidious appeared younger and non-deformed, despite his face having been horribly disfigured years ago. He explained to Ezra that he had had the remains of the Lothal Jedi temple moved to the Chimaera. The Emperor showed Ezra a portal to an alternate reality in which his parents were still alive. Ezra contemplating entering, but realized that doing so would mean he never joined the Rebellion, destroyed the temple. Sidious was infuriated by this and his hologram began changing rapidly between his non-corrupted appearance and his true form. He then ordered a group of royal guards to kill Ezra before shutting off the transmission. The guards subdued Ezra while a squad of stormtroopers shot at him, but Ezra managed to use the rubble from the temple to crush them and escape.
Battle of Endor
Four years after the destruction of the Death Star, Sidious personally visited Endor as the Second Death Star was being built to oversee its completion.
During the Battle of Endor, Vader brought his son Luke Skywalker to Palpatine in an effort to turn Luke to the dark side, leading to a lightsaber duel between them. Luke nearly killed Vader but refused to finish him off. Enraged, Sidious tortured Luke with Force lightning. This led to Vader becoming Anakin Skywalker again and turning against the evil Emperor, killing him by throwing him down a reactor shaft. This would ultimately cost Anakin his life as well. With the Sith eliminated, the Empire began its collapse.
- He is voiced by Sam Witwer in the Season Two premiere "The Siege of Lothal". In Season Four, in the episodes "Wolves and a Door", "World Between Worlds" and "Family Reunion - and Farewell" he is voiced by Ian McDiarmid, who portrayed him in the films. Witwer’s lines as Palpatine were later re-recorded by McDiarmid, and this version of the Siege of Lothal is how it was released on Disney+.
- When Palpatine appears on the viewscreen in "Empire Day", the HoloNet News depicts him as young and handsome instead of his current deformed state, a practice employed by many real-life tyrants using state-run media. He would later alter his appearance in a similar fashion via the Force when he appeared in hologram form in "Family Reunion - and Farewell".