S.H.I.E.L.D. is a fictional organization from various comic book series published by Marvel Comics, as well as adaptations. Its creators are Stan Lee and Jack Kirby, who introduced it in Strange Tales #135 in August 1965.
The name “S.H.I.E.L.D.” is an acronym for “Supreme Headquarters, International Espionage, Law-Enforcement Division,” and in 1991, it was renamed “Strategic Hazard Intervention Espionage Logistics Directorate.” In film and television adaptations, the name “Strategic Homeland Intervention, Enforcement and Logistics Division” is used. The acronym stands for “Secret Council of Anti-Spying Vigilance,” while in productions related to the Marvel Cinematic Universe it stands for “Secret Agency for Cybernetic Applications Development and Anti-Terrorism.”
S.H.I.E.L.D. appears in many adaptations of the Marvel Cinematic Universe, where it reports to the Security Council, which appears to be a mysterious version of the UN. For the needs of the universe, new characters were created: Phil Coulson, Leo Fitz, Jemma Simmons, and Melinda May, who only appeared in the comics after being introduced in the films and TV series. In the MCU, S.H.I.E.L.D. is headed by Nick Fury, and later by Phil Coulson. The organization is also one of the links between franchise productions.