"Your work here is finished my friend. Piss off. Send me one of those delightful Ewok women."
- -The Emperor to his apprentice, Darth Vader.
The Emperor was the most powerful man in the Galaxy for a few years.
Rise to Power
Like most citizens of Naboo, The Emperor's first job was as a handmaiden working for King Veruna. While he enjoyed dressing in elaborate robes, he found the work- a combination of standing silently and rebuffing the king's sexual advances- to be unfulfilling. He saw an opportunity for advancement when senator Vidar Kim mysteriously died. Running on a platform of making Naboo important, The Emperor was easily elected as Naboo's junior senator.
At some point he decided to become a Sith Lord, being trained by Darth Plagueis, whom he met on a cruise. He also nearly suffered a blow to his political career he may never have recovered from when he was caught by authorities drunk in his hotel room with a hooker. It was the hooker that created the scandal as much as Palpatine's practice of urinating on her, while telling her, "It's okay, it's okay." He then twisted her ear like a toilet flusher. The issue was put to rest when the hooker was found decapitated, seemingly by a lightsaber.
Palpatine was able to ween himself off of hookers, but he would struggle for the rest of his life with his addiction to alcohol and urinating in inappropriate places.
Finding life in the senate to be as boring as life as a handmaiden, The Emperor decided to have some fun. To do this, he hired a bunch of stupid Neimoidians to go invade Naboo for no particular reason. Then he exposed Chancellor Valorum to purple kryptonite, which destroyed his superhuman political abilities. The resulting power vacuum coupled with sympathy for Naboo allowed The Emperor to be elected as Chancellor of the Galactic Senate.
The Clone Wars
The Emperor was not easily entertained, so even his powerful position began to grow boring. Like any bored politician, he decided to go ahead and start a huge costly war. Since there really wasn't anyone to fight, he hired Count Dooku, a former vampire, wizard and Jedi Knight, to get together an army of poorly designed robots and aliens. The Clone Wars were a great marketing success, as the Emperor was able to sell millions of Jedi and Clone-themed action figures and T-shirts. Unfortunately the marketing potential for the aliens and robots was not strong. The Emperor decided to have them all killed rather than risk their action figures continue to be ridiculed.
Birth of the Empire
When the Jedi learned of The Emperor's plans to end the war, they decided to arrest him- because suddenly they were interested in law enforcement. Mace Windu, Kit Fisto, and a couple of other freaky alien Jedi went into his office and stood around waiting to be killed. The Emperor easily killed all four, then declared himself The Emperor of the Empire. His first act was to have most of the Jedi killed. Some senators objected to what they saw an abuse of power, but most of them seemed OK with it. Eventually The Emperor dissolved the senate so that he wouldn't have to put up with their belly-aching any more.
He was also finally able to be himself and would often let the public see his secret persona of drunken asshole. Palpatine loved to down several pints and then take his shirt off before urinating on furniture, or sometimes people. What could they do about it? He would also occasionally yell, "look at me!" then execute anyone who looked.
The Emperor decided he'd spend all of the Galaxy's resources building ridiculous military technology. Very little consideration was given to practicality. One of his favorite innovations was the Death Star. He also was a fan of large vehicles that walked on legs rather than flying or using more practical wheels. Presumably he enjoyed watching them fall over when they stepped on ball bearing. He had a complete set of The Empire's Funniest Military Mishaps on DVD.
After the destruction of the first Death Star, The Emperor let his apprentice Darth Vader run around the Galaxy in an absurdly oversized ship chasing after the punk who blew it up. This led to one of the only Imperial successes, as a force of giant walking transports defeated a group of rebels hiding in a snow fort.
Since he was never able to hang out on the first one, The Emperor decided to build another, even bigger, Death Star, and use it to intimidate people who he didn't like- which included almost everyone who wasn't a white male human.
Fall of the Empire
The Emperor had a private throne room built on new Death Star, so he could hang out there whenever he wanted. He found these accomodations quite satisfying except that his private toilet frequently clogged. This was just the excuse he needed to cut loose and have his way with someone's couch.
Lowly Sanitation manager Stab Podgorney came home one night to his quarters on the second Death Star to find a withered old man peeing in his laundry hamper. Stab exclaimed, "Hey!"
Palpatine turned suddenly at the intrusion, and immediately stripped naked before pouncing on Podgorney and beating the crap out of him. After the fourth or fifth punch, Palpatine finally stopped urinating as well. When he was finished, he spat on Stab's swollen face, and sauntered out into the hallway naked as the day he was born. These incidents were what kept the Emperor sane during this stressful years of being leader.
Since he wanted to have something to watch while he was at the Death Star, Palpatine leaked the location of the Death Star to the Rebels, in order to incite a battle. This plan worked out well, but Darth Vader threw The Emperor down an open shaft because he was shooting lightning at Vader's son.
After the Emperor died, the Death Star was destroyed, and the Empire that he had worked so hard to build folded like a cheap suit.
The Emperor did not come back to life. Ever. Sure, there was that guy that claimed to be a clone of The Emperor, but it all turned out to be a hoax for a cheap HoloNet reality show, Who Wants To Be the Next Emperor? It was canceled halfway through the second episode when it was beaten in the ratings by a 3,700-year-old rerun of Married ... With Mynocks (granted, it was the episode where they did the crossover with Ryloth Vice).
He was remembered as someone who became very powerful very quickly, then kind of crapped out, like Pete Rose.
Powers and Abilities
As a powerful Sith Lord, he could do all kinds of freaky stuff, like shooting lightning out of his fingers. Perhaps his greatest power, however, was his ability to disguise himself by putting on a black hood and making his voice sound slightly more creepy.