Early into the proceedings of “You Can Call Me Bill,” Alexandre O. Philippe’s documentary about the nonagenarian actor William Shatner, the term “Shatnerian” is discussed as a method of acting. What might it mean and how does one go about describing it?

Mr. Shatner is incredulous: “People’s supposed imitation of me is, I don’t know, I don’t hear it.” Whereupon we see a clip of a genre movie stalwart, Bruce Campbell, explaining the venerable icon’s mannerisms and cadence. Mr. Campbell’s impression of Mr. Shatner is spot on, very funny, and done with evident love.

How genuine is Mr. Shatner in his incomprehension of the Shatnerian? A few moments after that clip, we see him performing at the Just For Laughs Comedy Festival. With the help of a slide presentation, he insists that “when I speak I never ever, ever talk like. Every. Word. Is. Its. Own. Sentence.” 

Then there was that sterling moment in the otherwise forgettable Eddie Murphy and Robert De Niro vehicle “Showtime” (2002), in which Mr. Shatner played a television director trying to get an authentic performance from the real-life cop portrayed by Mr. De Niro. “This guy,” he opines with an admirable deadpan, “is the worst actor I have ever seen.” 

That clip isn’t included in “You Can Call Me Bill,” but there are snippets of Mr. Shatner’s various television commercials, almost all of which succeed on the basis of self-parody. The man knows the difference between being an actor and hamming it up. Which isn’t to say Mr. Shatner hasn’t become more eccentric as he’s aged; he’s more portentous, too. Mr. Phillipe’s picture is a portrait of an old man in blowhardish fettle.

The documentary isn’t a complete or, perhaps it is better said, conventional portrait. Although “You Can Call Me Bill” is touted as “an intimate exploration of the life and career,” it’s not as full an accounting as a Trekkie might hope for. 

Sure, there are snippets from the original “Star Trek” (1966-69), as well as moments gleaned from Mr. Shatner’s turn as Denny Crane in “Boston Legal” (2004-08) and, less so, “T.J. Hooker” (1982-86). And who could forget that episode of “The Twilight Zone” in which he played Bob Wilson, a man whose fear of flying is compounded by his spotting an alien on the plane’s wing? 

Movie clips are peppered throughout, including a passing moment with Spencer Tracy in “Last Judgment in Nuremberg” (1961) and, to less stellar effect, starring as a begrudging Satanist in “The Devil’s Rain” (1975), a Z-grade potboiler. Yet what about the man’s questionable forays into pop music? Although Mr. Shatner is seen doing recitations with the National Symphony Orchestra at the Kennedy Center, we don’t hear of his punk-wise collaboration with Ben Folds, “Common People.” Really, it’s pretty good.

What do we get in “You Can Call Me Bill?” Childhood trauma touched upon; a glancing mention of Mr. Shatner’s Jewish upbringing; a thoughtful exegesis on his acting heroes, Laurence Olivier and Marlon Brando; the time he had to go on for an ailing Christopher Plummer in a stage production of “Henry V”; and how to go about portraying the captain of a starship: “As long as he has a command presence, he can be a joker.”

Most of the time we get Mr. Shatner in a philosophical mood. As the only person interviewed in the movie, he rambles on — I’m sorry, pontificates — ike an admixture of Henry David Thoreau, Kahlil Gibran, and Henny Youngman. Lest you think the last analogy is pejorative, know that Mr. Shatner spends a good hunk of time deconstructing Youngman’s signature joke, “Take my wife, please.” 

Mr. Phillippe has granted Mr. Shatner an indulgence and let him run with it. Showbiz mavens will be disappointed in the film’s lack of career detail and, let’s be honest, the absence of celebrity gossip. I mean, don’t we all want to know more about Mr. Shatner’s backbiting relationship with a “Star Trek” co-star, George Takei? Should you be one of the millions of fans who have a soft spot for the actor who embodied the trials and tribulations of James T. Kirk, you’ll forgive “You Can Call Me Bill” its digressions.