Palpatine is a fictional male Naboon senator turned Emperor of the Galaxy in the Star Wars series. The character was portrayed on screen by Ian McDiarmid. His allegiance / loyalty is to The Old Republic. Palpatine was a Senator for the planet of Naboo before being elected as Vice Chancellor of the galaxy. After Palpatine becomes Vice Chancellor and killing off as many Jedis as possible, he turns himself into an Emperor. As Palaptine's alter ego, Darth Sidious, Palpatine orchestrates crisis after crisis and at each time, Palpatine gets promoted or gains more powers. Palpatine is played in all the three prequel films and star Wars VI - Return of the Jedi by actor Ian McDiarmid. The original version of Empire Strike Back, the holographic Emperor was played by Clive Revill but he gets airbrushed out and replaced by Ian for the special editions, Clive was unable to play the Emperor in Return of the Jedi so had to step aside for Ian McDiarmid. Throughout every appearance, he was only referred to as Palpatine, in October 2014, Palpatine finally gets a firstname and its Sheev.
Right from an early point in the sequels, Palpatine starts influencing the young Anakin Skywalker. Over the course of the films, Palpatine manages to exert more and more influence. It starts subtly at first, telling Anakin to be the Vice-Chancellors envoy on the Jedi Council, something that troubles Yoda and Mace Windu but Anakin is allowed onto the Jedi Council but isn't afforded the title of Grand Master like the other Jedis on the council.
When Palpatine reveals that he is a Sith Lord, at first Anakin is taken aback and reports Palpatine to Mace Windu. However, when Palpatine says he can save Padme Amidala from death, not even the words of Mace Windu can prevent Anakin turning to the Dark Side and becoming Darth Vader.
The Sith Rule of Two had been in existence for many generations, long before Palpatine became Lord Sidious. It had been started by Darth Bane and continued since that time with Master and Apprentice. Palpatine's master had been Darth Plagueis the Wise before Palpatine killed Plagueis and took on the role of master. Palpatine's apprentice was Darth Maul who didn't last long against Jedi's Obi-Wan Kenobi and Qui-Gon Jinn in the first episode of the prequels. Palpatine had Count Dooku as his apprentice with his Sith name being Darth Tyrannus for the second and third films..
Palpatine had wanted Luke Skywalker to kill him and therefore Darth Vader would become the new Master and Luke be the new apprentice but it didn't work like that in the end.
Palpatine is just a Senator at the start but by the end of the film, he has managed to become Vice Chancellor after the current Vice Chancellor is unable to deal with the unfolding crisis. As Darth Sidious, Palpatine instructs Darth Maul to prevent Amidala from seeking support from the Galactic Senate. The crisis that Palpatine created was to persuade the Trade Federation to increase taxes on Naboo and then blockade the planet but Queen Padme Amidala wasn't going to agree to the charges.
Now firmly established as Vice Chancellor Palpatine, his Senate powers begin increasing until eventually he has his own army of clones. With seemingly great reluctance, Palpatine uses the clone army to attack the Separatists who are bent on causing a schism in the galaxy.
At the start of the film, Palpatine has been kidnapped by the separatist leaders Count Dooku and General Grevious and held on a battleship above Coruscant. Anakin Skywalker, R2-D2 and Obi-Wan Kenobi manage to get into the battleship to rescue the Vice Chancellor. Palpatine persuades Anakin to behead Dooku whilst Obi-Wan is unconscious. After the rescue, Palpatine resumes his duties as Vice Chancellor. Over the course of the movie, the Vice Chancellor's influence over Anakin grows to an extent that when Mace Windu arrives to arrest the Vice Chancellor, Anakin finally makes the jump to the dark side therefore becoming Darth Vader.
The only time that Palpatine is ever seen wielding a light sabre is when Mace Windu arrives to arrest the Chancellor on the charge of being a Sith Lord. Palpatine bites back by saying it is treason. Palpatine is able to despatch two of the Jedi Knights who had accompanied Mace Windu for the arrest but Mace Windu is a little more challenging. When Palpatine looses his lightsaber, Palpatine uses his Force electricity to try to kill Mace. Sadly the energy is consumed by the lightsaber which ages Palpatine considerable. Mace wants to kill Palpatine because he's too dangerous to put on trial but Anakin disagrees. Palpatine manages to persuade Anakin to chop off Windu's arms after which Palpatine then levitates Mace out of the Window.
Palpatine christens Anakin, Darth Vader and tells Darth Vader to go to Mustafar and kill the remaining leaders of the Separatists which Darth Vader duly obliges. After the battle between Darth Vader and Obi-Wan Kenobi ends, Palpatine senses this and goes to Mustafar to pick up the badly burned body and turn him into the black-helmeted villain that we all know.
Before Palpatine visits Mustafar, he is engaged in another lightsaber fight with Yoda, the only fight between these two Force powered individuals. The fight ends in a dead heat in the Senate chamber. After that point, Yoda decides to go into exile on Dagobah.
Although Palpatine is secured in the position of being the Emperor, he doesn't appear in the film. His red Royal Imperial guards do make an appearance and so does Darth Vader, as for the dark lord himself, he doesn't appear in the film which is a shame. Palpatine gets only a mention which is a shame considering how important he is to the whole Star Wars universe.
When the Han Solo movie named imaginatively as "Solo, a Star Wars Anthology" comes out, it is unlikely that Emperor Palpatine would appear in the film. Palpatine never had any dealings with or was ever interested in Han Solo.
Palpatine appears as a hologram as Darth Vader talks to his master about the current state. In the original film, the role of Palpatine was played by Clive Revill. As Clive wasn't able to take up the role again for Return of the Jedi, the role went to Iain McDiamind and the rest is as they say is history.
Emperor Palpatine arrives on the Death Star to see how things are progressing. Palpatine believes he has foreseen the forthcoming battle between the Rebel Alliance and the Empire. Palpatine believes that the end of the Rebel Alliance is soon and wants to watch. When the young Luke Skywalker is bought before the Emperor, he wants Luke to join the Sith. Palpatine wants Luke to fight his father Darth Vader but Luke will not do so until Emperor discovers Luke has a sister then Luke attacks Darth Vader.
Darth Vader is beaten and his hand has been chopped off by Luke Skywalker and the Emperor Palpatine demands that Luke kills his father which Luke refuses to do. When the Emperor starts to fire lightning at Luke, Luke turns to Darth to plead for help. Eventually, the pleading by Luke Skywalker works and Darth Vader picks up the Emperor and throws Palpatine to his death.
There had been speculation that Palpatine may have managed to resurrect himself and become Supreme Leader Snoke but so far those rumours have not been shown to be correct. Supreme Leader Snoke took on the command of the Empire remnants better known as the First Order. Snoke was just as badly disfigured as Palpatine but that's the only similarity so far.