NOT MANY actors get the privilege of reprising a role after a three-decade hiatus. In the case of Mark Hamill, though, who returns in full as Luke Skywalker this weekend in “The Last Jedi,” the true privilege belongs to the filmgoer.

It can sound strange, given his 40-year association with the farmboy-turned-Jedi role, but in this eighth main Star Wars movie, Hamill fairly resonates as a revelation.

The Luke of the Original Trilogy had a highly pitched energy and eagerness — he often was like a scampering puppy sliding through the whiz-bang action (and oft-stilted dialogue) of a space western. And Hamill, who had built up a résumé of television one-shots at that point, had the lightness of youth and idealism that befit playing boy adventurer.

Not that Star Wars creator George Lucas quickly spotted Hamill’s fitness for the role during the mid-1970s auditions.

“Lucas was such a brain-in-a-jar during casting, saying so little and giving no signs of interest, that Hamill thought he’d blown it,” Brian Jay Jones, the Maryland-based author of “George Lucas: A Life,” tells The Post’s Comic Riffs. “In his first audition, he was hustled out almost before he’d had a chance to finish his lines.”

But wise Lucas collaborators later found a way to get Hamill back before Lucas’s eyes, and the playful chemistry of Hamill, Carrie Fisher and Harrison Ford beat out another casting triad that included Christopher Walken and an underage Terri Nunn.

Hamill worked to elevate his acting with each film in the Original Trilogy, and then, after 1983’s “The Return of the Jedi,” he began to recede from the center spotlight.

What Hamill began to become in the early ’90s, though, was one of the hardest-working voice actors in Hollywood. His scores of credits included “Batman: The Animated Series,” “Robot Chicken” and “Justice League,” as he became particularly known for masterfully voicing the Joker.

All those years of voice work, it turns out, helped deepen Hamill’s best instrument, as he found new tones and colors in his barrel-aged throat. The former high-register “farmboy” could now boom with low and cackling menace.

Then came 2015, and the return of Leia (Carrie Fisher) and Han (Harrison Ford) in “The Force Awakens.” But in that film, we barely glimpsed Luke.

Rian Johnson’s “The Last Jedi” was built to be Luke’s movie, and so Hamill is given long, poignant scenes to flesh out a ravaged, spiritually defeated Jedi in exile.

Hamill now commands the screen, looking especially haunted during Johnson’s generous use of extreme close-ups.

“I think he’s giving his best performance ever,” “Last Jedi” producer Ram Bergman, Johnson’s frequent film partner, tells Comic Riffs.

The actor can now deliver so much with facial nuance, and when his voice and countenance are working in riveting harmony, this Hamill is a pillar of gravitas.

“It’s exciting just to see him back again, especially as the grand old man of the trilogy” nearly 35 years later, Jones says. “Hamill is the unappreciated hero of the Original Trilogy; everyone makes fun of him for his dialogue, and Ford gets all the glory, but Hamill is really working.

“He’s the emotional heart of the original three [films], so I’m so thrilled to see him again.”

And when Hamill gets a climactic “Last Jedi” scene that will stand alongside Luke’s most iconic moments ever, we are witnessing an actor performing at his peak. His every acting tool has been refined to the point of great command. And his rolling voice lingers till the battle is complete.

The rest, so powerfully, is silence.

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