Nick Fury (MCU)

Overview
Perhaps the greatest espionage agent in the world, Nick Fury is a former solider, covert operative, and head of S.H.I.E.L.D., the Strategic Homeland Intervention, Enforcement, and Logistics Division. He led S.H.I.E.L.D. for many years and leading the organization through numerous crises and spearheading the Avengers Initiative.

Fury has made guest appearances in numerous films of the Marvel Cinematic Universe including Iron Man; Iron Man 2; Thor; Captain America: The First Avenger; The Avengers; Captain America: The Winter Soldier; and Avengers: Age of Ultron as well as the Agents of S.H.I.E.L.D. TV series; all of which has been portrayed by Samuel L. Jackson.

Background
Nick Fury is a major supporting character based on the comic book character published by Marvel Comics. He debuted in Sgt. Fury and his Howling Commandos #1, published in May 1963 and was created by Jack Kirby and Stan Lee. Sgt. Fury was the leader of an elite U.S. Army unit in World War II but he proved so popular that he ultimately transitioned to the "modern age" of Marvel superheroes; as a WWII veteran who had been promoted over the decades, transitioning into becoming an espionage agent akin to James Bond and then as the leader of the elite S.H.I.E.L.D organization.

As the leader of S.H.I.E.L.D., Nick Fury has been a major part of the Marvel-verse for decades; often acting as an intermediary between superheroes and the U.S. Government. He has also made numerous appearances in various Marvel animated television programs and films over the decades as well, even starring in his own feature film Nick Fury: Agent of S.H.I.E.L.D (1998).

Trivia

 * In 2000, Marvel Comics decided to create the "Ultimate Marvel" imprint which was an alternate universe series which was a modernized update of the original Marvel-verse. For this series; the writers who were huge fans of Samuel L. Jackson (with his permission) used his appearance for the Ultimate Nick Fury to differentiate between the two separate universes as the original was Caucasian.  As an in-joke in the Ultimate Comics; Nick Fury once mentioned that if there were a film made about them, only Samuel L. Jackson was good enough to portray him.  As it turns out, he was right.
 * The overall popularity and recognizability of Samuel L. Jackson as the character of Nick Fury in the Marvel Cinematic Universe has led Marvel Comics towards "retiring" Fury and replacing him with his son; Nick Fury Jr. who is a half Caucasian and African-American character, patterned after Jackson and is now a major supporting character of the Marvel-verse.

Quotes

 * Until such time as the world ends, we will act as though it intends to spin on.
 * "I've got my eye on you."  ―Nick Fury to Iron Man; Iron Man 2