The Avengers are a team of superheroes and the protagonists of the Marvel Cinematic Universe (MCU) media franchise, based on the eponymous team from Marvel Comics created by Stan Lee and Jack Kirby in 1963. Founded by S.H.I.E.L.D. director Nick Fury, the team is a United States–based organization composed primarily of superpowered and gifted individuals, described as "Earth's Mightiest Heroes", who are committed to the world's protection from a variety of threats.

The Avengers are depicted as operating in the state of New York: originally from the Avengers Tower in Midtown Manhattan and subsequently in the Avengers Compound in Upstate New York. Arranged as an ensemble of core MCU characters originally consisting of Tony Stark / Iron Man, Steve Rogers / Captain America, Thor Odinson, Bruce Banner / Hulk, Natasha Romanoff / Black Widow, and Clint Barton / Hawkeye, it later expands to include 16 total members.

Regarded as an important part of the franchise, they are central to the MCU's first 23 films, collectively known as the Infinity Saga. Avengers teams from alternate universes were depicted in subsequent MCU properties across the Multiverse Saga, including appearances in the Disney+ animated series What If...? (2021–2024) and Doctor Strange in the Multiverse of Madness (2022). A new incarnation of the Avengers is set to return in Avengers: Doomsday (2026) and Avengers: Secret Wars (2027). Both films will be part of the MCU's Phase Six, concluding the Multiverse Saga.

Following the formation of Marvel Studios as an independent film studio by Avi Arad, the head of Marvel's film division, producer Kevin Feige envisioned creating a shared cinematic universe to introduce the Avengers, similar to Stan Lee and Jack Kirby's comic books in the 1960s. Once Feige became studio chief in 2007 and formed his creative team, his strategy involved creating individual films for each major character in Phase One, beginning with Iron Man (2008) and concluding with The Avengers (2012). Casting for the original six members occurred from 2006 to 2010, beginning with Robert Downey Jr. as Iron Man and concluding with Mark Ruffalo replacing Edward Norton as the Hulk by 2010. Successive MCU installments introduced new members, with actors from other MCU films reprising their roles. Following the financial and critical success of The Avengers, a sequel, Avengers: Age of Ultron (2015), was subsequently developed, with Aaron Taylor-Johnson and Elizabeth Olsen joining as Pietro and Wanda Maximoff, respectively. Captain America: Civil War (2016) was influenced by the "Civil War" comic storyline, depicting the breakup of the Avengers and introducing Tom Holland as Peter Parker / Spider-Man. Avengers: Infinity War (2018) and Avengers: Endgame (2019) concluded the Infinity Saga and depicted their disbandment. The film Captain America: Brave New World (2025) depicts the team restarting under the leadership of Anthony Mackie's Sam Wilson / Captain America, while the film Thunderbolts* (2025) sees members of the Thunderbolts team form a separate faction dubbed the "New Avengers".

The four Avengers films are currently the third highest-grossing superhero franchise and the sixth highest-grossing film franchise of all time, grossing more than US$7.7 billion. The Avengers have received praise as a group from critics, particularly for their dynamic together, with Endgame receiving praise from critics as a conclusion for that iteration of the team. Due to their successful introduction, other film studios decided to create their own shared superhero universes, notably DC Entertainment and Warner Bros. Pictures, which announced plans to release a film for the Justice League. Avengers Campus, a series of attractions at various Disney Parks, opened in June 2021 at Disney California Adventure, while an immersive family dining experience called "Avengers: Quantum Encounter" debuted at the Worlds of Marvel restaurant in the Disney Wish cruise ship in July 2022.

The Avengers' story in the MCU takes place in the Earth-616 universe. The fictional biography below includes events that happened to the team from more than one Earth-616 timeline, as well as events that occurred in alternate universes.

In 1995, S.H.I.E.L.D. director Nick Fury creates the Avengers Initiative, envisioning it as a group of heroes working to respond to planetary threats, following the appearance of Carol Danvers and naming it after her U.S. Air Force callsign, "Avenger". Years later, Fury assesses various individuals for it, including Tony Stark and Steve Rogers. Stark's membership is declined after a negative report by S.H.I.E.L.D. agent Natasha Romanoff. The World Security Council wanted Emil Blonsky to join, but rejected it after Stark deters Thaddeus Ross from the idea, hiring Bruce Banner instead.

In 2012, the Asgardian Loki teleports to the Joint Dark Energy Mission Facility on Earth, where he steals the Tesseract and brainwashes Clint Barton and Dr. Erik Selvig using his scepter. Subsequently, Fury recruits Stark and Banner to locate the Tesseract. Rogers, Romanoff, and Stark apprehend Loki, but are disrupted by Thor's arrival. This leads to confrontations between the group, exacerbated by the revelation that S.H.I.E.L.D. is using the Tesseract to create weapons of mass destruction. Barton attacks the Helicarrier, causing Banner to transform into the Hulk and cause damage. After Loki kills S.H.I.E.L.D. agent Phil Coulson, the team unites to avenge him, with Romanoff freeing Barton from the scepter's control. Rogers then recruits Barton to the team as a new member. The Avengers confront Loki, who opens a wormhole using the Tesseract and begins an invasion with his Chitauri army, starting a battle. Stark introduces the team to Loki by referring to them as "Earth's Mightiest Heroes". Eventually, the World Security Council launches a nuclear missile towards Manhattan, but Stark intercepts and flies it through the wormhole, destroying the Chitauri mother ship and stopping the invasion. Romanoff closes the portal with the scepter and the team apprehends Loki, who is taken back to Asgard.