All too often, the inclusion of a rock classic in a movie soundtrack can feel like a lazy way to underscore whatever the filmmaker wants an audience to feel in the moment. But when Thor: Ragnarok pulls out Led Zeppelin's "Immigrant Song" — not once, but twice — it's the perfect musical companion to one of the more satisfying battles in the sprawling Marvel Cinematic Universe. As it turns out, director Taika Waititi didn't even know he had clearance for the track until the movie was almost finished.

"Immigrant Song" was always part of Waititi's concept for the film, which finds Thor stripped of his magical hammer, orphaned and marooned on a distant planet while his secret sister, Hela the Goddess of Death, invades their Asgardian home. But Led Zeppelin's rights management team is notoriously finicky when it comes to signing off on song approval, and as Waititi told Business Insider, it wasn't until the Zep camp actually caught a glimpse of the movie that they agreed to clear the track.

"When we had the first cut of the trailer and showed Led Zep, they understood how perfect the song was for this character," Waititi explained. "I think it wouldn't have happened if we didn't start the conversation with them really, really early on."

As Waititi added, it also helped that he was making the movie for Marvel, whose corporate parents at Disney have some of the deepest pockets in the movie industry. While the studio isn't known for overpaying, the surviving members of the band aren't exactly hurting for cash, so the director assumes there wasn't much in the way of negotiations. "I have a feeling if you want to entertain that idea of using their music, you have to have the money," said Waititi. "No negotiations. Offer it to them straight up. They're worth it!"

It all added up to one of the coolest musical moments in a 2017 blockbuster movie — and a happy ending to a long-held dream for Waititi, who had "Immigrant Song" on the soundtrack even when he put together his first pitch reel for Marvel execs. Ironically, many of the Marvel reps present for the meeting weren't even familiar with the track.

"They were like, 'Oh that’s really cool. That’s a cool song. What’s that?'" he recently recalled. "I was like, [deadpan] 'It’s 'Immigrant Song', Led Zeppelin, one of the most famous songs of all time.' They were like, 'Oh cool, never heard it before, very cool.'"

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