An unexpected duo comprising an iconic doll poised to color the world pink and a scientist who played a role in inventing the atomic bomb proves to be an unlikely but potentially blockbuster combination.

Millions of moviegoers are expected to dive into the very different worlds of "Barbie" and "Oppenheimer" as the two blockbusters premiere on Friday, with many planning to see both – a five-hour feat – the same day.

More than 200,000 viewers across North America are projected to have already signed up for a "same-day double feature" of both movies this weekend, said Michael O'Leary, president of the National Association of Theatre Owners.

This adds to millions of others worldwide planning to catch them on separate days, he said.

The parallel opening has sparked a flurry of memes – with social media users parodying their outfit transitions between the movies – and even merchandise, in a phenomenon dubbed "Barbenheimer."

Pop culture moment

The online marketing for "Barbie" has "caught fire in its own way, appealing to a generational audience and an underserved female audience," while director Christopher Nolan has his own fanbase, noted Shawn Robbins, chief analyst at Boxoffice Pro.

"They intersected in a way that turned it into this really unpredictable pop culture moment, that has turned into the 'Barbenheimer' meme," he told Agence France-Presse (AFP).

This has "maybe elevated the profiles of both movies in a way that neither of them might have had, had they opened on different weekends," Robbins said.

David A. Gross of Franchise Entertainment Research added, "It's the moviegoers taking over and making it their own."

The films will help each other, not compete with each other, by creating excitement for moviegoing, he said.

"I can't recall anything like it" in recent memory, added Gross, noting that box office projections are already off-the-charts.

Robbins expects "Barbie" – a nearly two-hour tongue-in-cheek take that sees the doll plunge into the real world – could bring in over $140 million for the weekend.

"Oppenheimer," a three-hour historic thriller, could exceed $50 million for the weekend but was designed to play out over a longer period, he added.

While an actors' and writers' strike is underway, the casts of both films, including Margot Robbie, Ryan Gosling, and Cillian Murphy, participated partially in premieres.

'Completely different'

Consultant Melanie Kelley plans to see both films the same day with her friends, starting with "Oppenheimer" in the morning and then, after a long break, ending over dinner at the theater in a fuchsia extravaganza.

"These movies have a lot of hype around them because they're really interesting and completely different from each other. That, coupled with getting the chance to spend a day in a movie theater – I'm in," she told AFP.

The last she remembers of an opening weekend frenzy was going to see "Jurassic Park" as a child.

Kelley, 39, who is based in Colorado, has listened to a podcast about Robert Oppenheimer to understand his history, adding that she is curious to see how much filmmakers would delve into his personal life.

Meanwhile, she said: "Barbie's definitely been a huge part of my childhood, and I think the irony that (director) Greta Gerwig is going to bring to this movie will make it even more nostalgic for me."