Catwoman is often included. She has a complex relationship with Batman already, and in a crossover, she could bring her thieving skills and charm to interact with characters from other worlds. Maybe she teams up with a character like Black Widow from the Marvel universe in a heist - like scenario that involves elements from both their worlds.
Definitely Joker. He's such an iconic character in The Dark Knight universe, and when it comes to crossovers, his chaotic nature can create great interactions with characters from other franchises. For example, if he meets the Joker from the DC Animated Universe, it could be a really wild and unpredictable encounter.
Harvey Dent, or Two - Face, is another favorite. His fall from grace and his split - personality concept offer a lot of room for exploration. Fanfiction can delve into his recovery attempts or his further descent into villainy.
Definitely Venkman. His sarcastic and witty personality can create great interactions in crossovers. For instance, if he were in a crossover with the X - Men, his humorous take on the mutants' powers would be hilarious.
Hajime Nagumo from 'arifureta' is a popular choice. His overpowered abilities and his journey from being a weakling to a powerful hero make him an interesting character to put in crossovers. Yue is also very popular. Her magic and her relationship with Hajime can add a lot of depth to a crossover story. Another character is Shea. Her energetic and somewhat naive personality can create humorous and interesting interactions in a crossover.
Akagi is another fan - favorite. Her character has depth and mystery. In a crossover, she could be the key to unlocking some complex plotlines, perhaps she has a connection to a powerful artifact in another world or has some hidden knowledge that is crucial for the story.
In Ben 10 crossover fanfiction, many writers like to include Azmuth. As the creator of the Omnitrix, he has a wealth of knowledge and power. His presence can add a layer of depth to the story, especially when it comes to explaining the science behind the Omnitrix or helping Ben understand new alien forms. Also, Charmcaster is often included. Her magic abilities can create some interesting dynamics when combined with Ben's alien powers in a crossover.
Joker is definitely one of the most popular. His cool and mysterious demeanor makes him a great fit in various crossovers. Also, Morgana is often included as his sidekick. Another popular character is Makoto, with her strong - willed and intelligent personality.
Batman himself is obviously a must - include. His leadership and skills are central to the Batfamily dynamic. Also, Robin, especially Damian Wayne as his complex relationship with Batman adds a lot of drama. Nightwing is popular too, with his acrobatic skills and his own journey away from being Robin. Batgirl, like Barbara Gordon, is often included for her intelligence and fighting abilities. And Alfred, the ever - loyal butler, who often provides support and wisdom to the family.
John Connor is often a popular choice. His leadership skills and importance in the Terminator series make him a great character to bring into other fictional universes. For example, in a crossover with a superhero world, he could be seen as a strategist working with the heroes.
Definitely Balto himself. He's the main character and the centerpiece of any Balto - related fanfiction. Another popular character could be Steele. His antagonist role in the original Balto story makes for great conflict in crossovers. Also, Jenna is often included as she was an important part of Balto's story.
Sonic, without a doubt, is the most crucial character. But in addition to him, characters like Silver can bring a different perspective. His ability to manipulate time in a way could be incorporated into the Black Knight story in unique ways. Also, Rouge. Her thieving skills and her relationships with other characters can be a great addition. And don't forget about the characters native to the Black Knight world, like King Arthur - like figures, who can add a touch of medieval fantasy to the fanfiction.