Superman, Batman, even the Avengers, all operate in the public eye, working to save the innocent people of Earth from harm. But more often than not, there is a secret force working in the shadows. Heroes you don't know, and won't, unless they want you too. One such secret government force has been saving the day since 1965, do you know who this is?

SHIELD, created by Stan Lee and Jack Kirby, debuted in Strange Tales #135 in August 1965. It serves as an espionage, law-enforcement, and counter-terrorism agency that usually deals with paranormal and superhuman threats. Originally, SHIELD stood for Supreme Headquarters, International Espionage, Law-Enforcement Division. In 1991, it was changed to Strategic Hazard Intervention Espionage Logistics Directorate. However, within the Marvel Cinematic Universe, the acronym stands for Strategic Homeland Intervention, Enforcement and Logistics Division.

Throughout its existence, SHIELD has been most prominently led by Colonel Nick Fury. Other historically prominent members include Thaddeus "Dum Dum" Dugan, Gabriel "Gabe" Jones, Contessa Valentina Allegra de la Fontaine, Clay Quartermain, Jacob Strzeszewski, Jasper Sitwell, Sharon Carter, and Jimmy Woo. Although SHIELD has several fully equipped shelters around the world, the central base of operations is located in New York City.

ABC launched a television series based on the workings of the organization, entitled Marvel's Agents of SHIELD in 2013. Currently in its fourth season, Agents of SHIELD stars Clark Gregg, Ming-Na Wen, Chloe Bennet, Iain De Caestecker, Elizabeth Henstridge, and Henry Simmons. Many of the story arc's depicted on the series closely relate to the comic series, especially the current story line involving Life Model Decoy's.

Agents of SHIELD airs Tuesday's at 10 PM on ABC.