The most repeated story about the career of Alden Ehrenreich, an actor whose name is worth committing to memory now, is a story of discovery, a miracle of luck and circumstance not unlike Lana Turner’s at the soda fountain.

But because Mr. Ehrenreich, 26, is a young Jewish prince of the Palisades and our story begins in the early aughts, the soda fountain is a Los Angeles bat mitzvah and the discoverer is Steven Spielberg.

Mr. Ehrenreich is used to retelling the details, he said, though over the years, people have become more and more apologetic about asking for them again.

The broad strokes are these: At the age of 13, noodling around with a video camera, he and a friend made a funny video for the bat mitzvah of a friend of a friend. It was a surreal and haphazardly plotted love story, which began in the present and eventually cut to 20 or 30 years later, with Mr. Ehrenreich, in a kimono, screaming to stop a wedding.

“When we showed it to our parents, they said, ‘You look like a moron, you can’t let anyone see this,’” Mr. Ehrenreich said.

He was not even at the bat mitzvah where it was screened, but Mr. Spielberg was. A call from DreamWorks, the studio Mr. Spielberg helped found, and a meeting with its casting director followed.

Mr. Ehrenreich’s progress has been slower than that overnight-sensation story would suggest.

After the video, he spent years auditioning, bagging stray cameos on procedurals and in teen-friendly TV shows. He built himself up by gradual persistence, and though his name is not yet immediately familiar to you, it is to a handful of Hollywood heavyweights: Francis Ford Coppola, Woody Allen, the Coen Brothers, Warren Beatty.

“I think you’ve chosen a good person to be writing about,” Mr. Beatty said when a reporter called, citing Mr. Ehrenreich’s “unusual combination of sensitivity and intelligence and humor.” “My feeling is that he is going to be a major player in movies.”

That may happen sooner than later. Mr. Ehrenreich is suddenly being discussed all over Hollywood, as trade papers and gossip columns on both coasts trumpeted this week that he has landed the role of Star Wars’ Han Solo in the coming Solo standalone movie, scheduled for 2018, rumors of which have circulated for weeks. When asked, Mr. Ehrenreich said he could not say anything about it, though he did cop to being a Star Wars fan. (“Who isn’t?” he said. Star Wars vs. Star Trek? “Probably both.”) A representative for Disney, which distributes the Star Wars films and owns Lucasfilm, which produces them, declined to comment.

Before then — most likely — Mr. Ehrenreich will star in Mr. Beatty’s long-gestating film about two young strivers who arrive in Hollywood to work for the mogul Howard Hughes. (Mr. Beatty has had it in mind since the 1970s.) In April it was reported that the film would be released this fall, though Mr. Beatty said that a date had not been chosen.

Mr. Ehrenreich’s rise comes after a few starts that stalled. “Tetro,” a modest family drama by Mr. Coppola, was warmly received but played at only 16 theaters in the United States at its widest release. “Beautiful Creatures,” a big-budget supernatural teen romance, fizzled.

Then came Joel and Ethan Coen’s back-lot comedy, “Hail, Caesar!,” with a star-making turn for Mr. Ehrenreich.

“Hail, Caesar!” is a loving sendup of old Hollywood, a jaunty caper of kidnapping and Communist intrigue set at Capitol Pictures, a fictional studio. Its plot functions mostly as a way to cram a variety of 1950s studio-system genre flicks and scenery-chewing actors into a dizzy pastiche.

George Clooney does his best Charlton Heston in “Hail, Caesar!,” a “Ben-Hur”-ish film within the film. Scarlett Johansson vamps as an Esther Williams-style mermaid. Channing Tatum tap-dances a homoerotic homage to Gene Kelly.

Even in such company, Mr. Ehrenreich stood out. As the cowboy crooner Hobie Doyle, a Western actor shoehorned into a prim drawing-room comedy called “Merrily We Dance” (another film within the film), he made off with entire scenes.

He went nose to nose with Ralph Fiennes in what may be the film’s most endearing bit of shtick: a painstaking elocution lesson in which a country boy butchers a line (“Would that it were so simple!”) in attempted mid-Atlantic English.

“Hail, Caesar!” — the Coen brothers’ film, rather than the Capitol Pictures one — was met with mixed response (though it was a hit with many critics, wise to the countless Hollywood in-jokes). But Mr. Ehrenreich in particular, who took lessons in rope tricks (with both lasso and spaghetti), horseback riding, guitar and gun slinging to prepare, earned raves.

“Charming,” The New York Times wrote. “Superb,” Variety wrote.

“Alden is the kind of actor that steals every scene he’s in,” Mr. Clooney wrote in an email. “It’s so much fun to watch how hard he works and how effortless it seems.”

Hobie Doyle would seem an odd choice for Mr. Ehrenreich, a kid from Los Angeles (he attended the Crossroads School for Arts & Sciences, in Santa Monica, Calif., where Jonah Hill and Jack Black were also students). He campaigned for an audition and won the role — in part, one suspects, because he has such an affinity with old Hollywood himself.

Unlike many of his contemporaries vying to be X-Men or rom-com heartthrobs, Mr. Ehrenreich resembles the stars of an earlier era. At 26, his hair is already silvering, as if by force of will. Raised by movie-buff parents, Mr. Ehrenreich speaks worshipfully of Paul Newman and Jimmy Stewart, Frank Capra and Elia Kazan.

“When you watch a lot of movies as a kid, the stories do shape a little bit how you view the world,” he said.

Mr. Ehrenreich spent a few years at New York University but left in 2011, without completing a degree. Film was always the goal. “I just had a feeling of ‘I know what I want to do, and I want to start doing it again,’” he said.

In effect, he put himself through his own film school with Mr. Coppola, with whom he lived for weeks while preparing for “Tetro.” “I was young enough that I didn’t know not to pepper him with questions all day long, so that’s all I did,” Mr. Ehrenreich said. “All day long, I’m like, ‘What was Robert Duvall like? What was Pacino like?’ It was the greatest mentorship I could have ever imagined from essentially my favorite director of all time.”

He repeated the process with Mr. Beatty, over hourslong meetings and lunches at the Musso & Frank Grill in Hollywood.

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When Mr. Ehrenreich got the “Tetro” role, he had appeared in zero films. But he impressed one of its executive producers, Fred Roos, who has worked with Mr. Coppola on casting and production since “The Godfather.”

“I think he can be a real star,” Mr. Roos said. “You will build movies around him. I think he’s talented enough to bring off anything. One of my oldest friends in the business, who’s a movie star that never fit any mold, is Jack Nicholson. Alden kind of has the Jack personality from the get-go.”

Mr. Ehrenreich is not a star, yet. Despite the accolades for “Hail, Caesar!” his day-to-day life is not radically different. He still goes most days to the one-room office he rents in West Hollywood to read scripts and write, on the lot where, by coincidence, “Hail, Caesar!” was shot. (It is the site of the original United Artists, the studio founded by Mr. Chaplin and others.)

The office is so sparsely furnished as to be Kafkaesque, bare but for a cheap desk and two office chairs, an AM/FM radio and a college-dorm mini fridge plugged into one wall. The only bit of décor, balanced facedown against one wall, is the oversize prop poster for “Lazy Ol’ Moon,” a Hobie Doyle western glimpsed in “Hail, Caesar!”

Mr. Ehrenreich walks to work. The paparazzi have not yet noticed.

“Things changed a little bit, maybe, professionally, but I’m learning how much you are always ignorant of what the life of something is outside of it,” he said. “It starts from zero every time. Every time you finish, you’re unemployed.”

But whether he is aware of it, people are watching, inside the industry and outside of it. He has already shot the Iraq war drama “The Yellow Birds,” and Mr. Beatty’s film, whenever it arrives, will likely bring Mr. Ehrenreich even more attention. “I think it’ll be a real step up for him, as far as things being offered to him,” said Mr. Roos, who saw it in a private screening.

So for now, he is adjusting to life on the cusp of stardom.

“You get used to it, though I don’t think you ever really get used to it,” he said of seeing himself onscreen. “I remember the first time with ‘Tetro.’ It’s like when you look in the mirror at the end of a long day: That’s who I was all day? And it’s that, times 10.”