With the Secret Invasion series, Nick Fury is set to retake his place as a central character in the Marvel Cinematic Universe after having been absent for almost all of Phase Three.
Samuel L. Jackson can also now claim the title of the longest-serving actor in the franchise, having begun his run all the way back in 2008 with Iron Man's post-credits scene. Jackson's portrayal is in many ways the actor's own take, although there are several aspects of the comic-book versions of the character that he nails as part of his performance.
Intelligence
Being the head of a spy agency requires having intelligence of all sorts, but first and foremost it means being the smartest person in every room. Or, to use Nick Fury's own phrasing from Captain America: The Winter Soldier, one has to learn "to keep both eyes open."
Whether it's building in a secret shut-off for Project Insight tied to his damaged eye or being able to salvage an entire helicarrier, Nick Fury shows off his intelligence plenty of times in the MCU. It's a credit to Jackson that viewers always get a sense that his mind is turning, formulating, and reformulating plans even on the go. He also obviously gathers plenty of intelligence in the spy sense, as well going so far as to venture into space to learn more.
Seriousness
Spider-Man: No Way Home may have taught the MCU wall-crawler the true extent of great responsibility accompanying great power, but Nick Fury has understood this principle in some form throughout his career in espionage. For him, though, with great responsibility also comes great seriousness.
Nick Fury does have his moments of levity in the MCU, and even cracks a smile now and again, but for the most part, his demeanor is defined by seriousness. Samuel L. Jackson has threaded the funny/serious needle plenty of times before, and he brings it once again to Nick Fury, but for someone who has to consistently analyze threats to security, a guarded personality is almost a job requirement.
Rogue nature
One of the other spy-genre elements that seems to translate straight into Nick Fury is his ability to go rogue, even to the point where he seems to enjoy it at times. He undermines the World Security Council by sending Loki and the Tesseract with Thor, and the only way he's able to take down S.H.I.E.L.D. is because, while he runs the organization, he has contingency plans separate from it, including faking his death.
Still, there have been times when this was a disadvantage, since there are several Civil War and thus preventing the Avengers from dividing.
Lack of trust in others
At the same time, Nick Fury's rogue nature seems to in part stem from his line of work, where the mantra of any agent worth their salt seems to be "trust no one." Fury even indicates as much to Captain America when he says that the last time he trusted someone, he lost an eye.
Captain Marvel may have undone some of the implications of that line, but it still speaks to a deeper-seated unease Fury has with people. The whole reason he s the Orwellian surveillance of Project Insight is because, as he makes clear, he doesn't trust human nature. It's that blindspot (no pun intended) that almost leads to disaster, but that same distrust is also how Fury starts to unravel the truth. It may be necessary for the job, but it's definitely also isolating.
Secrecy
Of course, even without a distrust of others, Nick Fury would have an obligation as a spymaster to compartmentalize information, another term he uses in Winter Soldier when talking to Captain America about Project Insight. But this is set up in The Avengers when Tony and Cap uncover that S.H.I.E.L.D. is building Tesseract-powered weapons.
Some of Spider-Man: Far From Home. Nick Fury always has a secret or two up his sleeve, but he'd be a terrible Avenger because of it, as that team is built on trust; while they work with him, none of them can fully trust Fury.
Sarcasm
Perhaps the biggest coping mechanism for MCU characters is sarcasm, and Tony Stark is perhaps the only character who employs it more frequently than Nick Fury does. For Stark, it's more about his immaturity, the inability to take things seriously, whereas for Fury it seems to operate more as a stress relief because of his aforementioned seriousness. It's definitely an important character detail that needs to continue.
Nick Fury's use of sarcasm also stands apart from the traditional MCU formula humor because of how well Jackson delivers the lines, honed from decades of experience playing iconic characters who employ sarcastic quips. It also helps cut the character's tension a bit, making him a bit more accessible for moviegoers, as he's more than just an uptight military man/spy.
Tactical abilities
What makes him one of Samuel L. Jackson's most badass characters is Nick Fury's ability to handle himself in dangerous situations of several types, from the implosion of the P.E.G.A.S.U.S. facility in Avengers to the intense car chase in Winter Soldier.
If his intelligence makes a good spymaster, then Fury's tactical prowess makes him an impressively-effective field agent when he's placed in situations where he has to use those skills, whether it's outmaneuvering Norse gods or well-armed Hydra operatives. It's to the point where a fight with James Bond could be an even match, assuming they have access to the same level of gadgets in that fight.
The Eyepatch
The story behind how Nick Fury lost his eye in the MCU may differ significantly from the comics, but the monocular look has been part of the character for decades in the comics, and there was never any doubt it would feature in the movies.
While the eyepatch looks comic-accurate, the signature eyewear also puts a limitation on Jackson's acting ability, since one of his most expressive features (the eyes) is only half-available for use. Still, just as it doesn't hold Fury back in the comics, it doesn't hold Jackson back when he portrays the character on-screen; Fury is just as expressive as Mace Windu or Jules Winnfield.
Mission dedication
Nick Fury is willing to do almost anything to get his mission accomplished, whether it's putting his own life on the line to try to keep the Tesseract away from Loki or maintaining his faked death even after S.H.I.E.L.D. falls so as to hunt down remaining Hydra cells in Europe.
He also isn't above using underhanded tactics, either, like fabricating Coulson's Captain America cards having blood on them to inspire the Avengers, or putting the teenage Spider-Man in danger on a European vacation. (It may be Talos who does this, but it's on the real Fury's orders.) It's ruthless, but also what makes him so compelling.
Mentor role
There would be no Avengers without Nick Fury's proposal and follow-through on the Captain-Marvel-inspired Avengers Initiative, which stopped Loki and delayed, then eventually undid, Thanos's snap. But Fury is more than just the meeting organizer; he's the mentor figure, and the scene with Coulson's cards epitomizes that.
Also, from a story perspective, it's why he's out of Civil War, because he would have served as the father-figure who could have stopped the fighting. Tony may be upset in Iron Man 2 when he's rejected as an Avenger, but it's clearly in hindsight partly because respects Fury... to a degree. Still, Fury remains an indispensable MCU asset for a reason.
