The 84-year-old legend muses about the possibility of reinhabiting Capt. Kirk ('How would they handle it, in science-fiction terms? I'm older, I'm heavier'), Harrison Ford's return to 'Star Wars' ('He needed a new airplane'), his seances with DeForest Kelley ('He's haunting a southern mansion') and his feud with George Takei as 'Star Trek' turns 50.

"This really isn't the 50th anniversary," William Shatner deadpans as we sit down in his Studio City office to record an interview commemorating the 50th anniversary of the airing of the first episode of Star Trek, the cult TV series-turned-blockbuster film franchise. "It just got canceled, Star Trek — but we're in a time warp."

When those words come out of the mouth of the actor who brought to life Capt. James T. Kirk, a man who traveled through space and time as commander of the starship USS Enterprise, one almost believes them. But, as Shatner acknowledges over the course of our wide-ranging conversation, time most certainly has marched on.

He's now 84, "older and heavier." His two principal costars, Leonard Nimoy and DeForest Kelley, have passed away. And Star Trek has moved on without him, on screens big (with J.J. Abrams' 2009 Star Trek and 2013's Star Trek Into Darkness and Justin Lin's Star Trek Beyond, due out July 22) and small (CBS will kick off its All Access network with a Star Trek series in 2017). But Shatner's still standing, busy as ever and "filled with joy of life," he says, so he has decided to mark this major milestone by celebrating his collaborators on the franchise.

He has written a book, Leonard: My Fifty-Year Friendship with a Remarkable Man (out Feb. 16), about his "dear friend" Nimoy, who died last February. ("I'm referring to the brother that you grow up with, upon whom you can lean, or they, with abandonment, can lean on you.") And, through May 8, he is on a 100-city tour with Star Trek — The Ultimate Voyage, which celebrates the music of the franchise — and its composers, including Gerald Fried, Jay Chattaway, Dennis McCarthey, Mark Mckenzie, Cliff Eidelman, Ron Jones and the late Jerry Goldsmith — with performances by a live symphony orchestra paired with footage from the franchise. ("It's an extraordinary experience," promises Shatner.)

While much of our conversation pertains to Star Trek, we also talk about a lot of other aspects of Shatner's colorful journey to international stardom. A Jewish kid from Montreal, he first tried performing as a kid. "I got love and applause and my course was set," he recalls. "I never did anything else but act, write, direct, in some manner entertain you."

He performed over the radio as a teen, then in Shakespearean productions after graduating from McGill with a business degree, and subsequently in live television and on Broadway after relocating to New York. He became "quite popular" as a live TV performer, popping up in all of the great anthology series — in fact, it was on an episode of Playhouse 90 that he first crossed paths with Rod Serling, who would later cast him in two classic episodes of The Twilight Zone. His often parodied "manner of speaking" — stop-and-go, you might call it — originated during the original Broadway production of The World of Suzie Wong, as a means, he says, of keeping the audience off its feet enough to stick around. The fact that it continued on Star Trek, he says with a chuckle, is more attributable to his struggles to remember his next line.

Starting in the late 1950s, he appeared in a handful of movies, some very good — 1958's The Brothers Karamazov, 1961's Judgment at Nuremberg — others less so. But his big screen career never quite took off, which made him open to TV offers like one that came along in the 1960s from one Gene Roddenberry, inviting him to participate in a reboot of a failed pilot called Star Trek. "Everything congealed — everything came together — on that second bout," and the show was a go.

Though Shatner and his collaborators constantly lived in fear of being canceled due to poor ratings, he still remembers the experience of making the original Star Trek, which aired on NBC between 1966 and 1969, as a special one. "There were three leads in the show and the three of us got along extremely well," he says. "It was a well-written part — I got to do a lot of things, a lot of wonderful things, as an actor. That was a terrific three years for an actor."

After the show was indeed canceled, Shatner's life took a dark turn. His beloved father died. His marriage ended. And, typecast as Kirk, he struggled to find work and lived out of his car for 13 weeks while performing in summer stock productions. Of that time, he most remembers his "desperation to make a living, to keep my children alive, to pay the alimony, and to be able to eat sushi now and then," he says. "I was doing everything I could to sell entertainment."

Then, "out of the woodwork," Star Trek returned to TV in syndication and Shatner soared back to popularity, to an extent greater than ever before. "When it went into syndication," he recalls, "more people saw it, it was in a better time-slot and away we went." Soon, the newfound popularity of the series, as well as the blockbuster success of George Lucas' film Star Wars (1977), spurred Paramount Pictures to make Star Trek: The Motion Picture (1979), followed by sequels of widely varying quality, Star Trek II: The Wrath of Khan (1982), Star Trek III: The Search for Spock (1984), Star Trek IV: The Voyage Home (1986), the Shatner-directed Star Trek V: The Final Frontier (1989), Star Trek VI: The Undiscovered Country (1991) and Star Trek Generations (1994).

Major spoilers regarding Star Trek and Star Wars through the end of this paragraph: Capt. Kirk died in the 1994 film. This was not because Shatner wanted out of the franchise, he insists, as is rumored to be the reason why Han Solo was killed off in Star Wars: The Force Awakens. "Harrison Ford might have wanted out," Shatner says with a laugh, "but Harrison Ford accepted the job. He needed a new airplane after the one he crashed!"

Abrams, the man behind the most recently released installments of both Star Trek and Star Wars, met with Shatner about the 2009 film, but nothing came of it — and Shatner, who regards Abrams as "a master," completely understands why. "I don't know what they would do with me," he says. "What is it, 20 years later? When we finished our movies — the six movies I made — we were putting Kirk into glasses, graying hair, a little old... Of course, the two other characters — the actors — are no longer alive, so it leaves me to come back. And how would they handle it, in science-fiction terms? I'm older, I'm heavier, I'm — all the problems of age. So what did Capt. Kirk do? Die and age? Doesn't sound science-fictiony enough. I don't know. It seems to have beggared Abrams' imagination." He adds, "I would play an old Capt. Kirk, absolutely, but you'd have to have an interesting character, not a cameo like, 'Here I am, aren't I interesting!'" (As for the Lin film, he says, "I don't know anything about it.")

Shatner's good humor about himself — and yes, his willingness to do just about anything for a paycheck — has led to choices odd (he served as the voiceover announcer at the recent Critics' Choice Awards) and fortuitous. His self-parodying stint as a pitchman for Priceline led to David E. Kelley's offer for him to do The Practice and Boston Public, and he won Emmys for both. A 2010 profile of Shatner said of his portrayal of lawyer Denny Crane on both shows, "William Shatner the man was playing William Shatner the character playing the character Denny Crane who was playing the character William Shatner" — to which Shatner counters, "As far as I'm concerned, I'm doing the best I can with my limited resources."

Does Shatner still keep in touch with his Star Trek collaborators? He cracks, "I'm in touch with DeForest Kelley. I run seances around our dining room table, and he's very well — his spirit is in the south, he's haunting a southern mansion, but he's very happy. As for Leonard, he hasn't gotten in touch with me yet." What about the supporting actors, such as George Takei, with whom he has had a long and very public feud? "Simply put it, I don't see them," he says, before bursting into laughter and adding, "You might say I never saw them."

As for his life today, Shatner — who is married to Elizabeth, his fourth wife, and has three children — has nothing but great things to say: "Life today? I am so filled with joy of life — athletically, as well. I ride competitively on three types of horses, I'm in the winning circle a lot, I have love all around me, my family is here, I'm happily married, I'm gainfully employed, my mind is more creative now than it's ever been."

He's working on multiple books and comic books — he calls Zero G, which he wrote with Jeff Rovin, "a great science fiction novel." He rides motorcycles for long distances. He watches movies (he had a pile of documentaries on his desk) and has strong opinions about them (an Academy member, he hasn't yet seen The Force Awakens, is excited to see Brooklyn and thinks Mad Max: Fury Road was just "one big stunt"). He is active on Twitter, sometimes baiting Star Wars fans with images suggesting Star Trek is the better franchise (though he tells me, "All of that Twitter stuff is just having fun. Is Star Wars better than Star Trek? Who the hell cares?"). And, despite famously appearing in an SNL sketch in which he told "Trekkies" to "Get a life," he says he greatly appreciates those who appreciate him: "I'm totally grateful — have always been grateful."

Does the r-word ever cross his mind? "Retirement?" he asks. "How do you spell that?" Instead, he's making plans well into the future. "What I would like them to say 50 years from now" — when Star Trek marks its 100th birthday — "is, 'I can't believe he's still alive!'"