Marvel's Agents of S.H.I.E.L.D. may be off the air, but it's real-world namesake may live on in the defense forces of the United States and Canada.
The Strategic Homeland Integrated Ecosystem for Layered Defense is a potential component of NORAD, the aerospace agency that provides security for the two nations, reports CBC. This version calls for monitoring potential air, land or space-based threats to the two countries through real-time data analysis.
Marvel's version of S.H.I.E.L.D. first appeared in Strange Tales #135, cover dated August 1965, as a starring vehicle for Nick Fury, updating him from World War II-era soldier to the public director of the spy agency.
The acronym "S.H.I.E.L.D." then represented "Supreme Headquarters, International Espionage and Law-Enforcement Division," in the manner of Bond adversary SPECTRE (Special Executive for Counter-intelligence, Terrorism, Revenge and Extortion) and the 1964-1968 TV series The Man from U.N.C.L.E., which Stan Lee once cited as inspiration. (At first ambiguous, "U.N.C.L.E." was retconned to mean "United Network Command for Law and Enforcement.")
S.H.I.E.L.D. joined a wave of fictional underground agencies with acronyms, some serious, like T.H.U.N.D.E.R. Agents (The Higher United Nations Defense Enforcement Reserves), and some silly, like The Inferior 5 spoofs H.U.R.R.I.C.A.N.E. (Heinous, Unscrupulous Rats and Rogues Initiating Criminal Anarchy and Nefarious Evil) and C.O.U.S.I.N. F.R.E.D. (Competent Organization Utilizing Scientific Investigation for National Fiend, Ruffian and Evildoer Defense).
S.H.I.E.L.D. was soon integrated into the Marvel Universe as having international reach, fighting threats foreign and domestic, often with the aid of Captain America and other heroes. It was renamed "Strategic Hazard Intervention Espionage Logistics Directorate" in 1991. For the Marvel Cinematic Universe (MCU), the agency was introduced in 2008's Iron Man, with its name given as "Strategic Homeland Intervention, Enforcement and Logistics Division."
Source: CBC