Music of the Marvel Cinematic Universe

The music of the Marvel Cinematic Universe (MCU) covers the soundtracks of the American media franchise and shared universe, which is centered on a series of superhero films produced by Marvel Studios. The films are based on characters that appear in American comic books published by Marvel Comics. The soundtracks include the original scores composed by various composers for the films and television series of the franchise, as well as the songs that are heard in each film.

Ramin Djawadi provided the first MCU music with his original score for Iron Man in 2008. Alan Silvestri was the first composer to work on multiple MCU films, while Brian Tyler was the first composer to reference the work of another MCU composer when he quoted Silvestri's "Captain America March" in his score for Thor: The Dark World (2013) and he composed the previous fanfare for the Marvel Studios production logo from 2013 to 2016. Michael Giacchino has scored five MCU films, the most for any composer in the franchise, and composed the fanfare that has been used for the Marvel Studios production logo since 2016. Original music has also been composed for the Marvel One-Shots short film series and other related MCU projects, and original songs have been created specifically for use in the franchise.

The scores for every MCU film and television series have received album releases, and several compilation albums featuring existing songs used in the films have also been released. Critical response to the MCU's music has been mixed, with focus placed on a lack of memorable themes compared to other large media franchises and on the lack of continuity between works. Some critics have shown more appreciation for the work of more traditional composers like Silvestri, and for Tyler's attempts to establish a consistent tone and thematic continuity for the franchise.

Ramin Djawadi had been a fan of the character Iron Man as a child, saying that he always liked superheroes "that actually don't have any superpowers". After Iron Man director Jon Favreau's previous collaborator John Debney was unavailable to score the film, Djawadi sought out the role himself. Filming on Iron Man had already been completed by the time Djawadi joined the production, and rather than wait until he could see the completed film, as he usually would, Djawadi began "playing with ideas" as soon as he saw the first trailer. Due to time constraints and the final cut of the film changing until "the last possible minute", Djawadi had help with arrangements and additional cues from Hans Zimmer and Remote Control Productions. Rage Against the Machine guitarist Tom Morello, who makes a cameo appearance in the film, contributed guitar performances to the score.

Favreau had a clear vision of heavy metal music and guitars for the project, saying that Tony Stark was more of a rock star than a traditional superhero, and "there's Spider-Man, Batman and all these superhero movies. This superhero movie's different. I want to do something completely different, instead of going down the orchestral route. I want to do more rock and roll." Djawadi subsequently composed most of the film's score on guitar, before arranging it for orchestra. Djawadi composed several themes for the character of Tony Stark, representing his different moods and attitudes, all inspired by Robert Downey Jr.'s performance. Other themes for the film are "not so much character based, but rather plot based that carry you through the movie". Musicians John O'Brien and Rick Boston, frequent collaborators with Favreau, provided a big band-style arrangement of the Iron Man theme song from the 1966 cartoon The Marvel Super Heroes for a scene where Stark attends a casino.

Director Louis Leterrier's first choice for composer on The Incredible Hulk was Craig Armstrong, once the arranger for Massive Attack, a band Leterrier was fond of and had collaborated with on the 2005 film Unleashed; this choice had surprised Marvel, who often had directors asking for the likes of John Williams or Danny Elfman, and the studio was hesitant due to Armstrong's lack of experience writing for action films. Leterrier listened to Armstrong's previous music while planning and editing the film, and music editor Peter Myles used Armstrong's work and similar music by others in the film's temp score. Armstrong chose not to listen to the temp, or watch Ang Lee's Hulk, before composing the score, which he began in his home in Glasgow, Scotland, before moving to Remote Control in Los Angeles to be closer to the production. The score was recorded in four days, resulting in little time for adjustments on the day, forcing Armstrong to "create very specific demos" that were "completely accurate" for Matt Dunkley to orchestrate. Leterrier favored an orchestral sound over electronics, "because he didn't want the work to sound dated so quickly", though Armstrong did electronically enhance a lot of the orchestral recordings. Additionally, "about half the score" features various ethnic instruments performed by Pete Lockett.

When Armstrong first began working in Glasgow, he did so with three sequences which he called "the keys to opening up" the score: the Abomination and the Hulk's alley fight, "which was complex because of its choreography"; Bruce Banner and Betty Ross' reunion, "the romantic element of the score"; and the Hulk and Betty in the cave, which "combines The Hulk Theme and when Hulk and Betty are together, so the Bruce and Betty Theme was totally different than my music for The Hulk and Betty". For the Hulk's theme, Armstrong compared it to Williams' main theme for Jaws, with "simple notation" that "summed up the complete concept". The theme features a bass C note, with string glissandos up an octave and then back down to the original note. Other themes include Bruce Banner's theme, for "when he's alone and searching for the cure"; two theme's for the Abomination, a dark one for the soldier Emil Blonsky and a more aggressive one for when he becomes a monster himself (the latter is combined with the Hulk theme when those character's fight); the love theme for Banner and Betty Ross; and a scientific theme, for "when they are trying to crack the codes of the Hulk". Joe Harnell's "The Lonely Man" theme for the 1978 The Incredible Hulk television series is briefly quoted in the cue "Bruce Goes Home", with Armstrong playing the piano for the piece himself.

For the sequel to Iron Man, Debney returned to work with Favreau, replacing Djawadi as composer. Debney called his score for Iron Man 2 "quite different in many ways from the last score. This score while employing much guitar and more contemporary elements, it is also much bigger and darker in tone and scope." He described his music as "Led Zeppelin with an orchestra", and elaborated that "The two scores share a common pedigree [of rock-and-roll and electric guitar] but are generally different. They are different scores with different results." Debney was not influenced by the AC/DC soundtrack for the film, feeling that "the songs and score play two very different roles in the film", and unlike the previous score he used a large choir for some of the film's more dramatic moments. Morello returned to again contribute guitar performances for the film, this time collaborating with Debney to write some of the music itself, with Debney first composing the score, and then working with Morello on the guitar parts and "textures".