You could do a crossover with a post - apocalyptic world. Naruto characters find themselves in a world full of ruins and new threats. The oc could be a survivor from that world who teaches the Naruto characters new survival skills, and in return, the Naruto characters teach the oc about chakra and ninjutsu.
Another interesting concept is to have an OC gamer from a racing game cross over into a post - apocalyptic action game. The OC would have to adapt their driving skills to navigate the dangerous terrain filled with zombies or other threats. They could use their modified cars from the racing game as a weapon or a means of escape in the new world.
One idea could be to have an original character (OC) who is a powerful mage enter the DxD universe. The OC could bring unique magic that the DxD characters have never seen before, causing both confusion and excitement. For example, the OC might have the ability to manipulate time on a small scale, which could be a game - changer in battles or interactions within the DxD world.
One idea could be to cross your original character (OC) with the world of RWBY and have them be a transfer student at Beacon Academy. They could bring unique skills or powers from their own world, like a magic system that RWBY doesn't have. Another idea is to have the OC be from a different time period and get thrown into the RWBY universe, causing all sorts of chaos and new storylines. For example, an OC from a steampunk world with advanced machinery could introduce new tech to the RWBY characters.
One idea could be a Naruto and One Piece crossover. Naruto and Luffy could meet and have to team up to defeat a common enemy that threatens both their worlds. Maybe a powerful dark force that can manipulate the sea and the land.
A cool Harry Potter OC Crossover Fanfiction idea could be to have an OC crossover with the world of Middle - earth. Imagine an OC from Hogwarts traveling to Middle - earth and using their magic to help in the battles against Sauron. They could introduce wands and spells to the hobbits and elves. Also, a crossover with the world of Fairy Tail would be interesting. The OC could join the Fairy Tail guild and participate in their quests while also showing off the unique magic of the Harry Potter universe. And a crossover with the world of Howl's Moving Castle could be fun too. The OC could interact with Howl and Sophie and learn about their form of magic which is different from Hogwarts magic.
You could also create a crossover where the OC Jedi Master enters a parallel universe. In this universe, the rules of the Force are slightly different. For instance, the dark side might not be as malevolent as in the normal Star Wars universe. The OC would have to adapt to these new rules while still maintaining their Jedi values. They might encounter versions of familiar characters that are completely different in personality and abilities, which would make for an exciting and unpredictable story.
One idea could be to cross over a Kamen Rider OC with a well - known anime character. For example, a Kamen Rider OC with Naruto. The OC could use their Kamen Rider powers in the Naruto universe, facing off against ninjas. Another idea is to have a crossover with a superhero from Western comics. The Kamen Rider OC might team up with Spider - Man to fight a common enemy in New York City.
A great idea for a Fairy Tail OC Crossover Fanfiction is to cross your OC with characters from the world of One Piece. Imagine your Fairy Tail OC with their unique magic abilities on a pirate ship, sailing the Grand Line. They could have battles with the Devil Fruit users, using their magic to counter the strange powers. Or, consider a crossover with the world of Bleach. Your OC could end up in Soul Society and learn about the different forms of spiritual power there while also showing off their Fairy Tail magic. Maybe they could even form a team with some of the Soul Reapers to fight a common enemy.
One idea could be a crossover between Spider - Man and an original character (OC) who has the power to manipulate time. The OC could accidentally disrupt the timeline in Spider - Man's world, leading to all sorts of chaos like villains getting released early or important events not happening as they should. This would force Spider - Man to team up with the OC to fix the timeline.
Well, one interesting idea could be the combination of Naruto's ninja skills with the powers from another fictional universe. For example, if Naruto were to cross over with the Harry Potter universe, his chakra-based jutsu could interact in unique ways with magic. Maybe he could use his Shadow Clone Jutsu to confuse Death Eaters while wizards try to figure out how to counter it with spells.