Light himself could be an interesting crossover into the Phantom Thieves' world. His presence would disrupt the Phantom Thieves' idea of justice. He might see them as a threat to his new world order and try to eliminate them while the Phantom Thieves would see him as a dangerous and power - hungry individual who needs to be stopped.
L from Death Note would also be a great crossover character into the Phantom Thieves' world. His brilliant detective skills could help the Phantom Thieves in their heists in unexpected ways. He could analyze the cognitive worlds of the targets more precisely, and his unique quirks and mannerisms would add a lot of flavor to the Phantom Thieves' dynamic.
Joker from the Phantom Thieves would be really interesting. He has a mysterious and complex personality. If he were to cross over into the Death Note world, his skills in manipulating situations and people could put him in direct conflict with Light. He might be able to outwit Light in ways that others couldn't, and his sense of justice, which is more about reforming society on a personal level, would contrast greatly with Light's more extreme views.
Misa Amane could also be an interesting addition. Her love for Light and her possession of a Death Note would bring a different dynamic. In the wizarding world, she might be attracted to the power and mystery of magic. Her presence could create a love triangle - like situation among some of the Hogwarts students, or she could be used by dark wizards who learn about her Death Note and try to control her.
Touka Kirishima could also be a fascinating crossover character. She's a strong - willed and capable ghoul in Tokyo Ghoul. If she got her hands on the Death Note, she might use it to protect her friends and the ghoul community in a more discreet way compared to her usual more direct combat methods. It would show a different side of her character, as she'd have to be more calculating and less impulsive.
One idea could be a crossover where the Phantom Thieves enter the world of Death Note. They might try to steal the Death Note from Light to stop his reign of 'justice'.
I think Jack Sparrow from 'Pirates of the Caribbean' would be really cool to cross over with Hercules. Jack's wily and unpredictable nature would contrast with Hercules' more straightforward heroism. They could be on a quest for a magical artifact that has the power to either save or destroy the world. It would be full of adventure, humor, and unexpected twists.
I think Gandalf would be a very interesting character to cross over. He has so much wisdom and power in LOTR. In the Harry Potter world, he could share his knowledge of different magics and perhaps help Dumbledore in his fight against Voldemort. He could also introduce the concept of the greater good in a more profound way to the young wizards and witches.
Definitely Doctor Strange. He already has a deep understanding of magic in the Avengers universe. In the Harry Potter world, he could exchange knowledge with the wizards, learn new spells, and maybe even help improve the defenses of Hogwarts. He could also have some really cool battles against the dark wizards using his unique combination of magic and martial arts.
Hermione Granger would be really interesting. She could bring her intelligence and magic skills to the OITNB world. She might start a library or a study group for the inmates, teaching them about magic and also helping them with their own educational pursuits. Her strong - willed and determined nature would make her a force to be reckoned with in the prison environment.
Daenerys Targaryen in the 'Vampire Diaries' world would be fascinating. Imagine her arriving in Mystic Falls with her dragons. She'd be a force to be reckoned with. The vampires would be both intrigued and perhaps a bit intimidated by her. She could use her leadership skills and the power of her dragons to navigate the supernatural politics of Mystic Falls, and might even form an alliance with some of the vampires against common enemies like the werewolves or other dark forces.
Definitely Doctor Octopus. Imagine him getting his hands on some magic wands and using his mechanical arms to perform complex spells. He could be a really formidable villain in the wizarding world, and it would be exciting to see how Harry Potter and Spiderman would team up to stop him.
I think Harry Potter himself would be really interesting. Imagine him interacting with a character like Naruto. Harry has his own struggles with being the 'chosen one' in his world, and Naruto has a similar burden. They could share their experiences, and maybe Harry could learn some of Naruto's ninja techniques and apply them to his magic. It would be a really cool combination of two very different but also similar 'chosen one' characters.