Emperor Palpatine is the only villain who has appeared in as many "Star Wars" movies as Anakin Skywalker/Darth Vader. He's also been played by the same actor since 1983.
That actor is Ian McDiarmid, and he'd like to keep it that way.
In an interview with BBC Scotland's Timeline, McDiarmid spoke about playing the iconic character. He said for "Return of the Jedi," they wanted somebody much older, as Palpatine is supposed to be 120 years old.
But, the actor they hired originally couldn't continue on the project, so they cast McDiarmid, loaded him up with makeup and the rest is history.
As far as the main series is concerned, Emperor Palpatine is dead. There's no chance he'll come back for a future episode. McDiarmid did mention the possibility of appearing in an anthology movie, though.