Hydra is a fictional terrorist organization that appears in American comic books published by Marvel Comics). It is a malevolent and influential organization that has been wreaking havoc around the globe since World War II. Its name alludes to the mythical Lernaean Hydra, and its motto is "If a head is cut off, two more shall take its place"). The organization has appeared in various media adaptations, including films, television series, and video games, and it plays a major role in the Marvel Cinematic Universe)).

In the Marvel Cinematic Universe, Hydra is an authoritarian-subversive paramilitary terrorist organization bent on world domination. It was founded in ancient times, formerly as a cult. In the comics, Hydra is an organization that doesnt think humans can be trusted with freedom. They think freedom does more harm than good to the world. The battle cry of "Hail Hydra!" is another iconic saying within the organization, along with the green and yellow uniforms its agents often wear.