Outside of Leonard Nimoy’s Bel Air home, workers are busy constructing a new driveway, replacing flagstone with sleek cement as part of an ongoing conversion from Mediterranean to modern. Though the 78-year-old actor is also undergoing a metamorphosis of sorts, he isn’t paving over his past.

After a 19-year absence, Nimoy again dons pointy ears as a mature Mr. Spock in J.J. Abrams’ “Star Trek,” the highly anticipated science-fiction franchise reboot premiering May 8. A week later, he’ll originate the recurring role of genius gazillionaire William Bell at the end of the May 12 season finale of Fox’s wicked supernatural series “Fringe.”

“In both of these cases, I feel like I’m slipping into a very comfortable bathrobe or a very warm bath,” Nimoy said with a robust chuckle over a cup of coffee inside his house. “I had a great time on the ‘Star Trek’ movie. And I had a delicious time on this episode. I like the position they have given me. I like the enigma of this character.”

Bell, the former lab partner of unhinged scientist Walter Bishop (played by John Noble), has often been mentioned — but never seen — on “Fringe.” Astute fans know that Bell became one of the wealthiest men in the world after parting ways with Bishop and founding Massive Dynamic, an ominous corporation that dabbles in robotics, pharmaceuticals and weaponry.

“I’ve never played America’s richest man before,” Nimoy cooed.

The former “Trek” and “Mission Impossible” star has filmed one scene so far in New York with actress Anna Trov, who plays Olivia Dunham, an FBI agent assigned to investigate unexplained phenomena with Bishop and his son. After production moves to Vancouver for the second season later this year, Nimoy will appear in additional episodes “when they call me.”

Something about Bell is very different from any character Nimoy has ever played, but he wants to keep that under wraps. What’s not a mystery is why Nimoy was offered the part: He bonded with “Fringe” co-creator Abrams during his “Trek” resurrection. Nimoy had never seen “Fringe” before but was impressed with the show after watching a few episodes.

“It’s not unlike any other show that’s ever been done,” said Nimoy. “It’s just that the execution is so much more thoughtful and theatrical than what I’ve seen in the past.”

Abrams earned the admiration of Nimoy after filming his upcoming take on “Trek,” in which Nimoy shares the role of Spock with Zachary Quinto, the 31-year-old “Heroes” actor who portrays an unripe Spock. Quinto said he was able to understand the iconic half-Vulcan, half-human Enterprise science officer because he melded with Nimoy off screen.

“The physicality and the essence of Spock is very specific, and it’s as tied to his cultural identity and his social identity as it is to Leonard having created it,” said Quinto, who now shares something else with Nimoy besides Spock: Like Bell, Quinto’s evil character Sylar on NBC’s “Heroes” was in the shadows on that show before Quinto was cast in the role.

Nimoy, surrounded by art in his house — including many of his own photographs — said the version of Spock he’s portraying in the new film is more like who he is more than ever before because “I know where I’m going, and I know where I’ve been.” Other than the “Fringe” role and possibly another “Trek” film, Nimoy doesn’t have other on-screen commitments.

And that’s exactly the way he wants it.

“I like being here,” he said. “This is great place to spend time.”