If there is one thing people love to do it is to have the superhero's face a dark version of themselves. It is a way of having the heroes face a literal personification of their inner demons. Between films and comics, there are plenty of examples of this phenomenon.
Some work better than others, but each of them has its merits. It is interesting to see how the heroes handle facing the darkest corners of their personality and if it has long-term ramifications for them going forward.
7 The Sentry Vs The Void
Bob Reynolds has the unfortunate responsibility of being The Sentry. He is an ultra-powerful hero but with a literal manifestation of his dark side that comes to life. This manifestation is called The Void. For every act of good that The Sentry performs, The Void does one just as evil in order to counteract it. Sentry has fought the Void both as a physical confrontation between the two of them, but more often it is a mental fight. The Sentry battles every day in order to keep his darkness at bay, as if it gets loose it could destroy the world.
6 Logan Vs X-24
Logan was a masterclass in making a superhero movie. It showed the last ride of Hugh Jackman's Wolverine and it is by far the best X-Men movie. The one weak point of the film was when Wolverine fought a younger and more ferocious version of himself called X-24. Fighting X-24 showed Wolverine what he could have been, a mindless animal being aimed at targets to kill. While it wasn't the strongest part of the movie, the theme it represented couldn't have been presented better.
5 Captain America Vs Hydra Cap Pitted A Traitor Against A Patriot
When Steve Rogers uttered the words "Hail Hydra" it shook the comic book world. It was the start of the rewriting of Steve Roger's history and instead of him being a true red-blooded American, he was a traitor and secret Hydra agent. This move was extremely controversial and has not aged well in the eyes of fans. Hydra Cap took over the United States and eliminated his former allies. But the true Steve Rogers was able to crawl his way back out of the void and fought Hydra Cap for his legacy and the soul of America.
4 Spider-Man Vs Ben Reilly In A Story of Clones
During the 90s Marvel came out with the Spider-Man Clone Saga. This story is heavily debated among Spider-Man fans. It is either believed to be a huge storytelling mess or one of the great Spider-Man stories that helped expand the Spider-man universe. It featured the villain the Jackal, who started cloning people and eventually cloned Spider-Man.
He sent out attacks on the city and ended up convincing both Peter Parker and the clone Ben Reilly that they were both clones and had them fighting each other. The Clone Saga isn't the last time they would face off. They would fight again in the sequel Clone Conspiracy.
3 Iron Lad Vs Kang The Conqueror After His Younger Self Formed The Young Avengers
When the Young Avengers was formed it was Iron Lad that brought most of them together. He knew that they needed to be prepared for a threat that would come from the future. It turned out that Iron Lad was a young version of the time-traveling criminal Kang The Conqueror. When Kang came to the present it was Iron Lad that helped the Young Justice team to stand against him. He leads that charge and helped to save the present and make up for the failings of his older self.
2 Thor Vs Ragnarok After Civil War
Civil War was a huge event for Marvel comics, but Thor was mostly absent from the event. His main presence was from a clone of him that was created by Tony Stark in order to help him gain an edge over the other team of heroes. But, like with most cloning experiences, it went horribly wrong and Ragnarok turned to the dark side. After Thor returned he decided to put an end to this abomination. The clone can't hold a candle to the powers of a true Asgardian and Thor easily defeated him, putting an end to the reign of the horrible experiment.
1 Miles Morales Vs Miles Morales Clones During The Clone Saga
Marvel cannot seem to get away from the idea of Spider-Man and clones. After the controversial storyline Clone Saga, they decided to recreate it with Miles Morales. There have been three clones of Miles made, all with various extra abilities. They got the upper hand on Miles right from the beginning and have threatened both him and his family. Miles is new to the whole cloning problem, while Peter Parker is very much used to it so readers wait to see what the long-term effects of the new Clone Sage will be for Miles.