- "There was an idea, Stark knows this, called the Avengers Initiative. The idea was to bring together a group of remarkable people, to see if they could become something more. To see if they could work together when we needed them to. To fight the battles that we never could. Phil Coulson died still believing in that idea. In heroes."
- ―Nick Fury to the Avengers after Phil Coulson's death.[src]
Although the exact purpose of the initiative has not been directly explained on-screen, it is implied that it employs people with special powers and abilities to defend the Earth against threats that may be too imminent and massive to handle.
The Avengers Initiative is said to have once been been scrapped in favor of "Phase 2", which involves using the Red Skull's research of the Tesseract to develop and distribute weapons of mass destruction to combat extraterrestrial attacks, following the arrival of the Destroyer and Thor in New Mexico.
The operation was unofficially reactivated by Fury when Loki emerged as an international threat.
Those involved with the Avenger Initiative include:
Nick is the director of S.H.I.E.L.D. who takes professional and personal interest in the Avengers Initiative.
Nick Fury's right-hand woman.
Phil contacts Tony about his escape from the Ten Rings in Afghanistan and discovers Mjölnir in a New Mexican desert. It is revealed in the final episode of Season 1 of Agents of S.H.I.E.L.D. by Nick Fury that Phil himself, is an Avenger.
Selvig is brought in after being involved in New Mexico, Fury asked him to look at the Tesseract.
Natasha investigates the suitability of Tony Stark for the Avenger Initiative under the name of Natalie Rushmann.
As the world's greatest marksman and founding member, Clint is more than qualified to be an Avenger.
Steve was recruited by Nick for a new mission after involvement with WWII.
Tony is brought on as a consultant for the Iron Man suit by Nick Fury.
Due to gifted intelligence and exposure to gamma radiation, Bruce is recruited as an Avenger.
Thor is (perhaps informally) recruited as an Avenger, at least by the time Loki makes his attack on earth.
- The Avengers Initiative has a lot of resemblance to the Ultimates program in the limited series The Ultimates, in that the group is formed as a government-sponsored team to combat the threat of the Chitauri.