Movies based on comic books have held top spots at the domestic box office for four of the past five years, with“The Dark Knight” and “Iron Man” standing astride the heap in 2008 and “Iron Man 2” occupying the No. 3 berth last year. So what seasoned director wouldn’t crave a chance to helm a potential box-office behemoth like “Thor”?

Yet eyebrows have arched over the selection of Briton Kenneth Branagh to direct Marvel Studios/Paramount’s “Thor,” which opens nationally Friday in standard, 3-D and Imax 3-D formats — the first of the year’s spate of such films. The movie features Aussie hunk Chris Hemsworth in the title role, and its large and starry cast includes two Oscar winners, Anthony Hopkins and Natalie Portman.

Hollywood’s bet on a noted Shakespearean to raise the summer’s first tent pole is a huge one. Although Branagh has not brought a film based on Shakespeare to the big screen in over a decade — his “As You Like It” aired in 2006 on HBO — he remains best known as something of a latter-day Sir Laurence Olivier for directing and starring in versions of “Henry V” (1989) and “Hamlet” (1996). His last effort behind the camera was also based on a play, the 2007 remake of Anthony Shaffer’s “Sleuth.” (It bombed in the United States, grossing less than $350,000.)

Determining the cost of a project like “Thor” is always a matter of some conjecture, but according to Kevin Feige, the film’s producer and the president of Marvel Studios, “If you Google it, $150 million is the number bandied about.”

In a phone interview from Dubai last month — where he was changing planes en route to Sydney for the premiere of “Thor” — Branagh acknowledged that Marvel’s offer was “a very good surprise” and represented “a challenge as an artist.” The film contains more than 1,300 shots using visual effects, according to the director. He also noted another draw: the opportunity to live in Hollywood for a couple of years — a non-negotiable hardship, apparently.

But Branagh maintained that the film “was a subject I felt right for,” recalling a glancing familiarity with the central character during his youth, when comic books were an enthusiasm of his. “It would take me out of my comfort zone, but in a story I knew,” he said of directing the saga of the hammer-wielding god of thunder. “And I was aware of the myth. That led me to an informed hunch that it would be a great project for me.”

Marvel, which controls many of the best-known and most-lucrative comic book franchises, obviously concurred. “We want storytellers who can think outside the box, filmmakers who can bring a unique voice to the process,” Feige said.

“When Ken’s name came up, it was one of those times when you just stop — like when Robert Downey Jr. was first proposed to play Tony Stark in ‘Iron Man’ — and you go, ‘That’s an unusual idea, and it could be unbelievably perfect.’

“What Ken offered us was someone who was familiar with staying rooted in the drama and the interaction of the family. And that’s the crux of ‘Thor,’ which is the story of a father” — Hopkins as Odin — “and two brothers” – Hemsworth’s Thor and Tom Hiddleston’s Loki – “set against this massive canvas of other worlds and superpowers.”

Branagh sensed common ground with Marvel from the beginning. “I knew of their concerns about handling the drama in a royal family,” he said, “and I knew they were happy with someone who knew about working with that and fancy costumes. They also thought I would be part of what would attract actors — and that could only benefit, having real actors for the roles.”

The parallels to directing Shakespeare might sound forced, but Branagh insists they exist. “Prince Hal in the ‘Henry IV’ plays is as reckless as Thor is in the brutish beginning of our film,” he said. “There you have Hotspur as a rival; here we have Loki. Also, in ‘Hamlet’ and ‘Henry V,’ conflicts may change whole nations, and so it is in ‘Thor.’ The universe is at stake if Thor gets it wrong.”

Similarly themed movies based on comic books will follow “Thor” starting this summer, including 20th Century Fox’s “X-Men: First Class” (opening June 3), Warner Brothers’ “Green Lantern” (opening June 17) and Marvel/Paramount’s “Captain America” (opening July 22).

Joe Johnston, who is directing “Captain America,” comes to these kinds of projects with a deep background in the technology that helps define them — he won an Oscar for visual effects in 1982 for his work on“Raiders of the Lost Ark.” But he cautions against embracing such elements to the detriment of traditional cinematic values.

“On a big-budget film like this, having everything at your disposal is not always an advantage,” Johnston wrote in an e-mail. “Whether it’s [visual effects] or live action or animation, you have to be sure that every image you put on screen is moving the story forward. Just because you can do something doesn’t mean you should.”

That’s a lesson Branagh seems to have intuited.

“We were trying to make a great big summer movie,” he acknowledged. “Something people can just enjoy. Making all of that effort seem effortless was, I think, the biggest challenge.”