In Star Wars: The Rise of Skywalker, we learned that Emperor Palpatine survived the events of Return of the Jedi. While the movie didn't do a particularly good job of explaining what happened, various tie-in material explained that, during his fall, he essentially cast his soul into a cloned body that wasn't ultimately unable to sustain him.
Possessing a failed clone body as "Supreme Leader Snoke," Palpatine created The First Order and spent years trying to find a body that could grant him freedom from Exegol. Rey (the child of one of his failed clones) and Kylo Ren were set to factor into those plans, but the former ultimately defeated Palpatine and put an end to the villain once and for all.
During a recent interview, actor Ian McDiarmid was asked about his potential future in the Star Wars franchise. After acknowledging that the Emperor is dead, he teased the door being open to another return elsewhere in this Galaxy Far, Far Away's timeline.
"I think I have to accept that, thanks to my ungrateful granddaughter [Rey Skywalker], my annihilation was finally final," the actor started. "[But] of course [Darth] Vader is back in the new [Obi-Wan Kenobi] television series, so I suppose it’s not impossible that one day his mentor might be discovered once again skulking in the shadows."
If Palpatine is destined to make another cameo, then we'd bet on it actually being in Obi-Wan Kenobi. There's still room to explore the villain, and really no reason not to potentially elaborate on how he ultimately returned in the sequel trilogy in other projects.
We'll keep you updated as and when we learn more!