Avengers: Infinity War is an upcoming two-part American superhero film based on the Marvel Comics superhero team the Avengers, produced by Marvel Studios and distributed by Walt Disney Studios Motion Pictures. It is intended to be the sequel to 2012's Marvel's The Avengers and 2015's Avengers: Age of Ultron, with Part 1 and Part 2 serving as the nineteenth and twenty-second installments of the Marvel Cinematic Universe (MCU), respectively. Both Part 1 and Part 2 are scheduled to be directed by Anthony and Joe Russo, with screenplays by Christopher Markus & Stephen McFeely, and are expected to be filmed back-to-back, beginning in late 2016. Part 1 is scheduled to be released on May 4, 2018, and Part 2 is scheduled to be released on May 3, 2019.

Since their early films, Marvel Studios began planting the seeds for Infinity War by introducing the Infinity Stones, immensely powerful objects that if held together can grant its holder near omnipotence, as mcguffins: the Tesseract / Space Stone in Captain America: The First Avenger, Loki's Scepter / Mind Stone in The Avengers, the Aether / Reality Stone in Thor: The Dark World, and the Orb / Power Stone in Guardians of the Galaxy.^[2][3] Additionally, one Infinity Gauntlet, the glove designed to house the stones, is briefly seen in Thor, while a second is seen in possession of Thanos in Avengers: Age of Ultron.^[4] Thanos, the villain who in the comics covets the stones, was initially believed by many fans to be the antagonist of Avengers: Age of Ultron after making a brief appearance in The Avengers.^[5] However, Joss Whedon, the writer and director of the first two films, explained that "Thanos is more powerful. He is so powerful, he is not someone you can just try to out punch. Like in the comics, you want him to be threading through the universe and to save the big finale for the big finale."^[6] While all non-Avengers films leading up to Infinity War were considered set-up for the films, producer and president of Marvel Studios Kevin Feige noted that Black Panther in particular was "a very important" link to the films.^[7]

In June 2013, Robert Downey, Jr. signed on to Avengers: Age of Ultron, as well as a third Avengers film, to return as Tony Stark / Iron Man.^[8] The following May, Josh Brolin, signed a multi-film deal including both parts of Infinity War to play Thanos.^[9][10] In July 2014, Feige stated that there are "some notions" to where Marvel would want to take a third Avengers film and that the actors from the previous films are "locked up [with contracts] for Avengers 3 ". He also said, while no release date has been discussed, the studio was aiming for three years between Avengers: Age of Ultron and a sequel.^[11] In September 2014, Jeremy Renner revealed he was signed on for a third Avengers film, to reprise his role as Hawkeye.^[12]

In October 2014, Marvel announced a two-part sequel to Age of Ultron, titled Avengers: Infinity War. Part 1 is scheduled to be released on May 4, 2018, with Part 2 scheduled for May 3, 2019.^[13][10] After the announcement, Feige also talked about the scale of the film and the possibility of the characters from Marvel Television's Netflix Defenders series appearing, saying, "Infinity War is going to be big. There are a lot of people from the movies in Infinity War. A lot of it is about space, and a lot of it is about just what happens between now and then. But all of those things inhabit, however far on the outskirts, the same continuity. So certainly that opportunity exists." Feige also mentioned that Mark Ruffalo would return for Infinity War, reprising his role as Bruce Banner / Hulk.^[14] In November 2014, it was reported that Avengers: Infinity War – Part 1 and Avengers: Infinity War – Part 2 were scheduled to begin filming back-to-back in late 2015.^[15] Also in November, Tom Hiddleston signed on to return as Loki in Thor: Ragnarok as well as both parts of Infinity War.^[16]

In January 2015, Whedon stated that he was "very doubtful" that he would be involved with the two Infinity War films.^[17] By April 2015, Anthony and Joe Russo reached a deal to direct both parts of Avengers: Infinity War,^[18] with filming expected to begin in 2016.^[19] Whedon cited the series' increasing scale as to why he chose not to return explaining, "Every movie I have ever made has been an ensemble piece of increasingly enormous proportions... That many balls in the air, it's only going to get bigger with Infinity War. I'm not going to be able to give it what I would need to."^[20] Also in the month, Feige said the films would be two, distinct films "because they [have] such shared elements, it felt appropriate... to [subtitle the films] like that. But I wouldn’t call it one story that's cut in half. I would say it's going to be two distinct movies."^[21] While promoting Age of Ultron, Chris Hemsworth revealed that he and Chris Evans both had three films left on their contracts, which consisted of both parts of Infinity War as well as the third films of their respective franchises.^[22] At the end of April, Evans revealed that filming was scheduled to begin in late 2016 over nine months.^[23] By May 2015, Christopher Markus & Stephen McFeely signed on to write the screenplays for both parts of the film.^[24]

In September 2015, Feige stated the films would explore the visions the Avengers saw in Age of Ultron, saying going forward, "were those little visions? Is that kind of like your worst fears being projected at you? Is that a prediction of the future? Or is that a sense of an ending doom that haunts you and keeps you awake at night? I think that'll be something we have to explore in Infinity War to kind of figure out how literal or not those are."^[1] In December, Anthony Russo stated that integrating characters from the MCU TV shows into Infinity War would be "complicated", adding, "When we start to serialize the telling of stories it’s difficult. You have to have a lot of control and focus on the course of history. The films are controlled by a group led by Kevin Feige, so they function as a unit. Other products, even if they are from Marvel, are controlled by others."^[25]

Principal photography for both parts is scheduled to begin in late 2016 over nine months.^[23] In May 2015, the Russo brothers announced that both installments of Avengers: Infinity War would be shot using IMAX/Arri 2D digital cameras, thus marking the first time that a feature film will be shot entirely using IMAX cameras and its exclusive aspect ratio.^[26]