Hydra is a fictional terrorist organization appearing in American comic books published by Marvel Comics. Its name alludes to the mythical Lernaean Hydra, as does its motto: "If a head is cut off, two more shall take its place," proclaiming the group's resilience and growing strength in the face of resistance. Originally a Nazi organization led by the Red Skull during World War II, Hydra is taken over and turned into a neo-fascist international crime syndicate by Baron Wolfgang von Strucker. Hydra agents often wear distinctive green garb featuring a serpent motif. Hydra's plans for world domination are regularly foiled by Marvel Universe superheroes and the intelligence organization S.H.I.E.L.D.

The Red Skull is a supervillain appearing in American comic books published by Marvel Comics and its predecessor Timely Comics. In Captain America Comics #1, the Red Skull's secret identity was revealed to be George Maxon; It would be retroactively established that he was merely a decoy who was working for the real Red Skull. Albert Malik would later adopt the Red Skull mantle, only to be killed in a plot orchestrated by the original.