Sometimes a superhero movie is so successful that the way the movies portray events and characters ends up influencing the direction of the comics. The creation and evolution of comic books and film adaptations are a shared entity with comics creating lore for movies to adapt.
However, the movies can sometimes adapt things for the better that the comics even take from. In some cases, the movies are so much more popular and loved that they changed the future of the comics forever, for Marvel and DC franchises alike.
Blade (1998)
Marvel's dark half-vampire hero exploded in popularity after the 1998 movie starring Wesley Snipes. The character was never on the same level as Spider-Man or Iron Man prior and part of that is because Blade was rather different before his cinematic debut. When he was first created, Blade was unfortunately written as a stereotype of men of color at the time. He wore a green outfit and didn't even have his signature silver sword: he has wooden daggers.
After the Wesley Snipes movie came out, however, Blade would forever be depicted as the quiet Daywalker clad in leather, wearing sunglasses, and decorated in tattoos to resemble the beloved film counterpart in some way. Fans loved the darker tone with a no-holds-barred approach to the blood and gore that made Blade into a mix of action and horror that forever changed comic book movies in general. The new edgier design for Blade helped in turning the character into a modern icon.
X-Men (2000)
Due to rights issues with X-Men and Captain Marvel AKA Carol Danvers, the character of Rogue was altered for the 20th Century Studios movies. No longer did she have the super strength and flight that she gained from Captain Marvel. Instead, she simply had her powerful absorbing touch and was given a more modern gothic redesign. This would end up changing Rogue in the comics and animated shows in the following years to closer resemble her film counterpart.
It made sense since X-Men was one of the biggest films then and continued the streak of showing that comic book movies can be taken seriously. Some fans even liked the more modern take on Rogue, saying it made her relatable. In more recent years, Rogue has reverted to her old self since fans still love and appreciate that version, but Anna Paquin's version will always have its place in history.
The Dark Knight (2008)
For many, The Dark Knight changed comic book movies forever and helped revolutionize Batman for the modern era. The Joker as portrayed by Heath Ledger became a villainous icon, so much so that a similar Joker came out in the comics the same year as Brian Azzarello's Joker graphic novel. Fans were both enthralled and terrified by his Joker, taking a more realistic domestic terrorist approach to the character.
Batman has also taken from The Dark Knight in general, embracing modern technology and being decorated in advanced body armor. The Christopher Nolan films also helped in reshaping how fans view Lucius Fox, making him more involved with Batman's mission. Morgan Freeman is often viewed as the definitive version of Lucius Fox and it shows; that fans loved his witty remarks combined with genius intellect. Since then, many incarnations of Fox including the Arkhamverse use Morgan Freeman's version as a template.
Ant-Man (2015)
Darren Cross in Marvel Comics did not even have a supervillain alias before his introduction to the Marvel Cinematic Universe. Yellowjacket was one of many variants of Ant-Man himself in the comics. However, the Ant-Man movie changed it so that Darren Cross was the antithesis of Ant-Man, showing the horrific side of what Pym Particles can do. Darren developed the Yellowjacket out of spite for Hank and the Ant-Man.
Marvel seemed to like this idea because, in 2016, Darren Cross was revamped into the new Yellowjacket of the comics in Astonishing Ant-Man #12. Even though Yellowjacket was never a beloved villain in the MCU, his armor was eye-catching and was considered a clever way to introduce the moniker without making Hank Pym fall into villainy.
Superman: The Movie (1978)
It's surprising how many things people came from the Superman movies that are now canon. For example, in the comics prior, the Fortress Of Solitude was constructed by Superman without the help of crystals. Krypton was not a crystalline planet, Lex Luthor was not a stranger to Superman, and so much more. Today, many fans still consider Christopher Reeve to be the definitive version of Superman from his appearance to his acting to even the misconception that Superman can reverse time.
Now, many artists of Superman use Christopher Reeve in Lois is more than a damsel in distress, she's a dedicated reporter who doesn't take any nonsense from anybody, even the villains.
Iron Man (2008)
Jon Favreau's Iron Man was the movie that jump-started the Marvel Cinematic Universe into the juggernaut franchise that it is today. It told a rather loyal adaptation of Iron Man whilst putting a new spin on the character. It did, however, forever change the way how fans viewed one character. In the comics, Edwin Jarvis was the Stark family's loyal butler who helped take care of Tony Stark.
Jon Favreau felt this was too similar to Alfred Pennyworth of the Bat-Family, so he changed Jarvis into J.A.R.V.I.S., the artificial intelligence which evolved into The Vision. Most fans were completely fine with this change since the similarities to Alfred were always present and many instantly fell in love with Paul Bettany's smarmy responses as an AI.
Guardians Of The Galaxy (2014)
James Gunn wisely chose to make alterations because, before 2014, the Guardians Of The Galaxy were practically forgotten by comic readers. After the first Gunn film, nearly every member of the team was portrayed similarly to the movie. Fans instantly fell in love with Drax and his misunderstanding of metaphors compared to the much darker incarnation in the comics. The most influenced by the film was Star-Lord who was originally portrayed as a mix of James Kirk and Han Solo.
Now, Star-Lord is the funny yet dedicated leader of the Guardians that is more akin to the Chris Pratt version. It's simply a case where fans were not as familiar with the original Star-Lord, so the Christ Pratt version was accepted as the definitive version of Peter Quill. He delivered a charismatic yet hilarious performance as the character which combined with the character's love for music resonated with audiences.
Batman: Mask Of The Phantasm (1993)
This goes for Mask Of The Phantasm often a contender for the best DC animated film with fans, it too has had its impact on comics.
The titular villain known as The Phantasm was as dark as it was tragic with the backstory being almost the same as Bruce Wayne's but showcases what could have happened if Bruce had fallen from grace. Since that film, The Phantasm has been introduced into the comics, including the DC cyberpunk adventure of Batman Beyond. It featured Terry McGinnis going up against a new version of The Phantasm.
Black Panther (2018)
The the beautiful country of Wakanda and turned characters such as Okoye and Shuri into fan favorites. Though it is not a drastic departure from the comics, Letitia Wright's take on Shuri was much more lighthearted and quirky in personality.
Since the film came out, Shuri in the comics and other media have been closer to the MCU version. In the comics, Princess Shuri was depicted more as a cunning warrior who vows to be Wakanda's protector and honor her brother. Whereas the film version and newer comics depict her as the charming technological whiz who can create anything out of vibranium for Black Panther and herself to use.
The Avengers (2012)
In the Ultimate universe, Nick Fury was given a design inspired by Samuel. L Jackson which the movies used perfectly. The movie version of Fury became so loved that the Earth-616 canon even brought in the Jackson-inspired design. Even the way Captain America was drawn began to slightly resemble the likeness of Chris Evans' Steve Rogers who became a poster child of the MCU ever since his debut.
It was because of Tom Hiddleston's portrayal in the MCU, especially in the first Avengers film, that Marvel began portraying the character almost exactly like Hiddleston. Loki in the MCU had such an interesting character arc from a jealous Shakespearian villain with a smug attitude to a genuine anti-hero willing to save the universe; it's easy to see why fans loved him so much.