Wicked” happened backwards — at least compared to most other Broadway hits that have ties to Hollywood.

Everything from “The Lion King” to “Hairspray” to “Kinky Boots” started out as a movie first, and then found new life as hit stage musicals. But “Wicked,” based on the 1995 novel by Gregory Maguire, took the road less traveled: Movie producer Marc Platt and Universal optioned the property, but after an initial, abortive attempt at a movie, Platt and Broadway veteran David Stone teamed to develop a $14 million stage musical version, funded in large part by Universal.

And the rest, as they say, is $915 million in Broadway history — and $3.75 billion in box office worldwide. It’s a musical megahit that’s now guaranteed a movie adaptation, which will get the “Wizard of Oz” backstory to the bigscreen that had been its original destination all along.

Platt, who’s also been on the Broadway producing teams of “If/Then” and “Three Days of Rain,” has had a hand in movie-musical projects including “Into the Woods” as well as “Ricki and the Flash,” the Jonathan Demme/Meryl Streep film with musical elements (to be released Aug. 4) and “La La Land,” the upcoming Damien Chazelle musical starring Miles Teller (shooting this fall). He recalled that those early scripts for the potential “Wicked” film never quite hit on the heart of the story, which takes Oz’s Wicked Witch as a sympathetic protagonist and reveals her surprising friendship with Glinda the Good Witch.

“It planted a seed of a really interesting relationship between two seemingly opposite people,” Platt said. “But the screenplays didn’t feel like they had magic.”

Independently, composer Stephen Schwartz, whose Broadway track record by that time included “Godspell” and “Pippin,” discovered the novel and thought it would make a great musical — but found, to his chagrin, that Platt and Universal had already snapped up the rights.

Platt, however, decided to give the musical idea a shot — which is not a move Hollywood makes very often.

“I had a feeling that putting music into it would add some of that magic that was missing in the screenplays,” Platt said. “And in telling the story of the journeys of two separate characters, music allows for the kind of inner monologue that’s hard to get at cinematically.”

Besides that, pop culture’s highest profile version of the Oz stories is the legendary 1939 MGM movie — and putting the behind-the-flying-monkeys story onstage seemed like it might help “Wicked” distinguish itself as something very different from the Technicolor version.

With Schwartz, book writer Winnie Holzman and Stone on board, the musical’s development culminated in a 2003 opening on Broadway, where the production snowballed into the smash it is today.

“Wicked,” it turns out, wasn’t the last time Platt has shifted targets from screen to stage. In 2005, Universal shelled out big bucks to win the bidding war over Stephen Belber screenplay “The Power of Duff” — but the project stalled in the screenplay stage.

“The script never found its way,” said Platt, whose Marc Platt Prods. would have produced the film. “We never cracked the third act, and I wondered if it would work better as two acts, as a play.”

The resulting stage version, developed at the Powerhouse Theater in a workshop with Greg Kinnear, went on to premiere at the Huntington Theater Company in fall 2013 and began performances this week at the Geffen Playhouse.

As for “Wicked,” which is currently running in five productions around the world, the next logical question is: When’s the movie?

According to Universal Pictures president Jimmy Horowitz, the studio is “absolutely committed” to making the movie, but is putting the focus on getting it right. “I don’t think we’re ever going to set a date and try to make that date,” he said.

Platt, meanwhile, acknowledges that part of the challenge now is finding an inherently cinematic counterpart to the musical’s signature stage spectacle. “‘Defying Gravity’ is a big, theatrical, grand gesture,” he said. “In film, how do you match that?”

So while the “Wicked” movie is on the to-do list, don’t hold your breath just yet. “We’re enthusiastically moving it forward,” Platt said. “But we don’t want to get ahead of what is still a robust theatrical experience.”