Although Iron Man shares the same name as the famous song by heavy metal pioneers Black Sabbath, fans know that Tony Stark's favorite band is the legendary hard rock act AC/DC. The band's signature song "Back in Black" plays on the radio during the opening scene of the first Iron Man film, and the entire Iron Man 2 soundtrack consists of AC/DC songs. Not to mention when Iron Man makes his entrance in the first Avengers movie, it's to "Shoot to Thrill." The usages of AC/DC's music in the Iron Man movies make the band inseparable from the MCU.

AC/DC needs no introduction. The Australian group has survived for nearly five decades as one of the world's biggest bands, releasing music as recent as 2020 with the album Power Up. Iron Man obviously wasn't the first movie to use their songs, nor was it the last to reference them. But as a part of Iron Man's identity, AC/DC was not just important to the character but the MCU itself.

RELATED: Iron Man: Tony Stark Had the Marvel Universe's Worst Sidekick EVER

When it was announced that the band would release a compilation album as the soundtrack to Iron Man 2, director and actor Jon Favreau explained why AC/DC and the character were a perfect match. "He's Iron Man, he's Tony Stark, he's going to go a million miles an hour," he told the Los Angeles Times. Favreau recounted that seeing the band play their song "Shoot to Thrill" at a concert inspired Tony Stark's Iron Man 2 entrance, saying, "You know this is how he should show up, right in the middle of this and take the armor off. That's the Tony Stark version of doing things."

However, using songs from a band as popular as AC/DC in a movie is expensive. Favreau compared using "Shoot to Thrill" for Stark's grand entrance at the Stark Expo as the equivalent to making an expensive action scene. Thankfully, the band was on board with using their music for Iron Man 2 and even made a new Iron Man-inspired music video for "Shoot to Thrill" to coincide with the film's release.

RELATED: MCU Fans Petition Marvel to Resurrect Tony Stark With Los Angeles Billboard

While the Iron Man movie franchise was already successful by the sequel's 2010 release, the MCU was still young, and the likelihood of an Avengers movie was uncertain. Different studios still owned Marvel's most popular characters like Spider-Man and the X-Men at the time. Getting a band as iconic as AC/DC onboard with the Iron Man movies further legitimized Tony Stark and the MCU.

A few years after AC/DC's collaboration with Iron Man, another hero used a Led Zeppelin song in their movie. It's even more difficult to get Led Zeppelin, but in 2017, Thor: Ragnarok got permission for the "Immigrant Song." Had AC/DC not helped legitimize the MCU with the Iron Man 2 soundtrack, it's unlikely that Ragnarok would have been able to use the elusive Zeppelin song.

Even after Stark's death in the climax of Endgame, AC/DC still made a cameo in Spider-Man: Far From Home. As Peter Parker goes through Stark tech equipment for his new Spider-Man suit, Happy Hogan puts on "Back in Black." The young Peter Parker hilariously responds with "I love Led Zeppelin," not realizing that it's his mentor's favorite band. Tony Stark may have left the Marvel Cinematic Universe, but when an AC/DC song plays, it feels like he's back and better than ever.

KEEP READING: WandaVision Proves Once & for All That Tony Stark Was Right