Hamill played the character in five Star Wars movies; the original trilogy, The Force Awakens (albeit briefly) and The Last Jedi.
However he appeared to die peacefully at the end of the latter, with many assuming he would not be seen again.
But with Force Ghosts an established part of the franchise, could he still make an appearance?
Hamill took to Instagram and Twitter with a countdown image, declaring there to be 532 days until Episode 9 is out.
He captioned it: “Who’s counting? #9WillBeFineAllInGoodTime.”
John Boyega posted the same image to his own Instagram feed, sparking speculation among fans that some announcements could be imminent.
One person posted on a Reddit discussion on the topic: “I mean, this is pretty much confirmation Mark’s involved, right? There was no real doubt, especially with JJ [Abrams], but it’s nice to know that people aren’t gonna be let down.”
Another said: “He had his beard at the Solo premier. He hates the beard and only keeps it for filming.”
Asked recently by Collider if Luke will be seen one final time, Hamill seemed coy.
“I don’t know,” he maintained. “I’m the last to know.”
But hinting that a “surprise” is possible, he said: “I like it that way… I like surprises….
“When I know something, I’ll let you know.”
The actor had also recently hinted that his enthusiasm for Star Wars appearances has waned since the death of Carrie Fisher and departure of Harrison Ford.
“It [Fisher’s death] really has tarnished my ability to enjoy it to its fullest,” he told ABC News.
“You were asking earlier, ‘are you gonna be back’… I don’t care anymore on that level. Because Han Solo is gone, Luke is gone.
“You just can’t get the band back together the way you wanted it to be, and it shouldn’t be that way. It is what it is.”
Star Wars: Episode 9 is out on December 20, 2019.
