S.H.I.E.L.D. - Marvel movies
There were a lot of acronym-loving organizations, both crime-fighting and criminal, when S.H.I.E.L.D. made its debut appearance in Issue #135 of the Strange Tales comic in 1965. (Think The Man from Uncle and James Bond nemeses SMERSH AND SPECTRE.)
Back then it stood for Supreme Headquarters, International Espionage, Law-Enforcement Division. Now, in the age of Marvel superhero movies like Iron Man, Thor, and The Avengers, it stands for Strategic Homeland Intervention, Enforcement and Logistics Division. In any case, Nick Fury (Samuel Jackson) is still in charge.