S.H.I.E.L.D.
The acronym was for Supreme Headquarters, International Espionage and Law-Enforcement Division. It was changed in 1991 to Strategic Hazard Intervention Espionage Logistics Directorate. Within the various movies set in the Marvel Cinematic Universe, as well as many animated and live-action television series, the backronym stands for Strategic Homeland Intervention, Enforcement and Logistics Division.