Mark Millar is one of the most successful creators in comics, having created several successful series for numerous publishing companies. While he first rose to superstardom in the U.S. at DC Comics, his work at Marvel truly put him on the map.

RELATED: 5 Things The MCU Avengers Took From Ultimate Marvel (And 5 Things They Took From 616)

Yet despite his many hits at Marvel Comics, Millar’s influence on the House of Ideas remains overlooked. His series have completely changed the tone and landscape of the Marvel Universe repeatedly, and have served as the basis for several Marvel Studios and X-Men-related films. Looking back at his work, one can easily see the ways they left their mark.

10 Skrull Kill Krew: Jumpstarted Millar's Marvel Career, Spawned A Sequel, Quietly Tested New X-Men's Motorcycle Gang Look

Skrull Kill Krew vs. the Fantastic Four

Co-written by Mark Millar and New X-Men creator Grant Morrison, Skrull Kill Krew followed a group of humans who had gained shapeshifting powers after drinking milk from the Skrulls Reed Richards had turned into cows during Stan Lee and Jack Kirby’s Fantastic Four run.

Skrull Kill Krew was Millar’s very first work at Marvel, undeniably opening the door for his later, higher-profile work. The team returned during Secret Invasion, but the Krew had a much bigger influence than the otherwise-unrelated New X-Men, having been Grant Morrison’s first attempt at patterning superheroes after biker gangs.

9 Marvel Knights Spider-Man: Made Mac Gargan Venom

Marvel Knights Spider-Man cover: Spider-Man battles the Green Goblin

Mark Millar’s Marvel Knights Spider-Man was the first solo Spider-Man ongoing series for the Marvel Knights imprint. The writer’s time on the title very much echoed the format of other runs by high profile creators of the time, running 12 issues long and featuring virtually every major Spider-Man villain.

Though part of continuity, Marvel Knights Spider-Man was fairly self-contained, meaning it didn't greatly affect other comic titles. Its big legacy, however, was making Mac Gargan, a.k.a. the Scorpion, the new Venom. Gargan remained Venom for several years, becoming a major player in Thunderbolts, Secret Invasion, and Dark Reign.

8 Fantastic Four: Made Kid Valeria Richards A Genius (& Introduced The New Defenders)

Fantastic Four #554 cover by Mark Millar and Bryan Hitch

Though not as influential as others on the list, Millar’s run on Fantastic Four introduced a number of characters that would go on to appear in FF runs by other writers. Chief among them were the New Defenders, a superhero team from the future who later got its own series as Fantastic Force.

RELATED: Civil War: 10 Worst Things Iron Man's Side Did, Ranked

The most impactful development Millar introduced, however, was revealing that Mr. Fantastic and the Invisible Woman’s kid daughter, Valeria, had developed super-intelligence. Valeria Richards subsequently became a major player in the Marvel Universe and became the only Fantastic Four member to have a friendly relationship with Doctor Doom.

7 Ultimate X-Men: Modernized The Team, Inspired X-Men Legends & X-Men: Evolution’s Finale

Ultimate X-Men

The main Marvel Universe was fairly slow when it came to capitalizing on the first X-Men movie’s success. Mark Millar, however, used the movie as his sole inspiration for Ultimate X-Men, the second series of Marvel’s Ultimate line. The darker, hipper costumes, sharp dialogue, and new spins on characters like Marvel Girl, Wolverine, and Colossus made the series popular enough to even outsell the main X-Men titles and tonally paved the road for New X-Men’s debut a few short months later.

Millar’s Ultimate X-Men served as a visual inspiration for the X-Men Legends games, along with one of the closing scenes of X-Men: Evolution.

6 Enemy Of The State: Introduced Gorgon, Led To Spiritual Sequels & Parodies

Wolverine Enemy of the State 1

What if Wolverine switched sides? That was what Millar and John Romita Jr. asked themselves in “Enemy of the State,” a 12-issue storyline in which Wolverine was transformed into a superhero-hunting weapon by newcomer Gorgon, Hydra, and the Hand. The second half, “Wolverine: Agent of S.H.I.E.L.D., saw Logan, cured of his brainwashing, exact his revenge.

Plot points from Millar’s story were followed up on by later Wolverine writers, while Gorgon reappeared in Secret Warriors. Similarly, the story was paid homage in the All-New Wolverine story “Enemy of the State II,” and parodied in the Cable & Deadpool story “Enema of the State.”

5 Ultimate Fantastic Four: Inspired Both Fantastic Four Movies & Led To Marvel Zombies & The Maker

Ultimate Fantastic Four

Millar’s Ultimate Fantastic Four work was far more influential than some give it credit for. His and co-writer Brian Michael Bendis’ revised origin, in which the team obtained their powers through a teleporter mishap, was adapted fairly faithfully into the 2015 Fantastic Four movie, while a Doom with an organic metal body appeared in the 2005 version.

Millar’s Ultimate FF also greatly impacted Marvel’s comic line. The zombie universe he introduced in his second run became the focus of the extremely popular series of Marvel Zombies comics, while Millar and Bendis' Reed Richards became a major threat to Marvel’s entire multiverse when he reinvented himself as the Maker.

4 The New Avengers: Was Half Millar's Idea

New Avengers #1 cover by Brian Bendis and David Finch

The lion's share of The New Avengers’ success can be attributed to Bendis and his artistic collaborators, as well as the popularity of characters like Wolverine and Spider-Man. Yet the series began as a conversation Bendis had with Mark Millar at a 2004 Marvel publishing retreat.

RELATED: Ultimate Marvel: 5 Heroes More Powerful Than Their Mainstream Versions

While bemoaning how the Avengers didn’t really consist of Earth’s Mightiest Heroes (in their view), Millar remarked that he only bought Justice League of America as a child because he could get DC’s greatest heroes for the price of one comic. From there, the wheels started turning in Bendis’ head, and his Avengers revamp was born.

3 Old Man Logan: Inspired Hugh Jackman’s Last Wolverine Film & Was Brought Into Earth-616

Old Man Logan popping his claws

Movies are a frequent source of inspiration for Millar. “Old Man Logan,” for instance, was clearly inspired by the Clint Eastwood film Unforgiven, which featured a hired killer coming out of retirement. “Old Man Logan” followed the same premise, showing an older Wolverine joining Clint Barton on a dangerous trek to deliver the Super-Soldier formula.

While the story only lasted eight issues, its popularity led to Millar’s aged Logan returning during 2015’s Secret Wars: he eventually even joined the X-Men of Earth-616. The storyline also heavily influenced Hugh Jackman’s third Wolverine solo film, Logan, as well as All-New Wolverine’s final arc, “Old Woman Laura.”

2 Civil War: Became A Movie & Defined Three Years Of Marvel Stories

Captain America vs. Iron Man (Tony Stark) in Civil War #7's cover

The fact that Civil War inspired a movie of the same name should make its impact abundantly clear. Taking a cue from his own work on The Ultimates, Millar, with artist Steve McNiven, had heroes war over whether superhumans should register with the government.

Civil War served as the basis of the third Captain America film, reusing the central premise and even paying visual homage to the final issue’s cover. The miniseries also defined the main Marvel Universe’s trajectory for the next three years, splitting heroes into pro-registration and anti-registration teams until the comic series Siege. Furthermore, it inspired a sequel, Civil War II.

1 The Ultimates: Defined The MCU (& Redefined The Marvel U)

Ultimate Captain America

By far the most influential of Millar’s comics at Marvel, The Ultimates was the blueprint of the Marvel Cinematic Universe. Everything from the core Avengers roster to Captain America’s World War II uniform originated from Millar and Bryan Hitch’s Ultimates run. In some cases, scenes were directly lifted from the comic series, such as Bruce Banner becoming Hulk by falling out of a chopper. The biggest example of The Ultimates’ influence on the MCU was the casting of Samuel L. Jackson as Nick Fury.

The Ultimates also directly impacted the Marvel Universe, which began featuring more militaristic heroes and cinematic storytelling.

NEXT: The 10 Most Important Marvel “Wars” Ranked