S.H.I.E.L.D. is a fictional espionage and law-enforcement agency in the Marvel Comics Universe. Created by Stan Lee and Jack Kirby in Strange Tales #135 (Aug. 1965), it often deals with superhuman threats.
The acronym originally stood for Supreme Headquarters, International Espionage, Law-Enforcement Division. It was changed in 1991 to Strategic, Hazard Intervention, Espionage Logistics Directorate.
Within the various films set within the Marvel Cinematic Universe, the acronym stands for Strategic Homeland Intervention, Enforcement and Logistics Division.
S.H.I.E.L.D.'s introduction in the originally launched Strange Tales feature "Nick Fury, Agent of S.H.I.E.L.D." occurred during a trend for action series about secret international intelligence agencies with catchy acronyms, such as television's The Man from U.N.C.L.E. and James Bond's SPECTRE. Colonel Fury (initially the lead character of Marvel Comics' World War II series Sgt. Fury and his Howling Commandos) was reimagined as a slightly older character with an eyepatch (which he lacked in his wartime adventures) and appointed head of the organization. Some characters from the Sgt. Fury series reappeared as agents of S.H.I.E.L.D., most notably Timothy "Dum-Dum" Dugan, Fury's bowler hat-wearing aide-de-camp.
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Official Site: Marvel Comics
Researched by: Alpha Tiberius