One character that is often used is Cortana from Halo. Her intelligence and relationship with Master Chief can be a great addition to a crossover. In the Starcraft universe, she could interact with the AI units there. Then there's Fenix from Starcraft. His honor - bound nature and combat prowess would be cool to see in the Halo setting. Also, the Flood-infected characters in Halo could be a unique addition to a Starcraft crossover. They could pose a new kind of threat to the Starcraft races, and seeing how the different factions deal with them would be engaging.
Master Chief is definitely one of the most popular. He's the face of the Halo series, so fans love to see him in crossovers. Cortana is also a popular choice. Her complex character and her relationship with Master Chief make for interesting crossovers. The Arbiter is another character that often features. His unique backstory and his role in the Halo universe can add a lot to a crossover story.
In Halo Warhammer 40k crossover fanfiction, the Librarians from Warhammer 40k are quite popular. Their psychic powers can lead to some really cool interactions with Halo's technology and characters. They can sense things in the Warp, and how would that work when dealing with the more scientific Halo universe? Cortana from Halo is also a favorite. Her artificial intelligence is something that doesn't really exist in the same way in Warhammer 40k. So seeing her interact with the various tech - priests or even daemon - possessed entities could be really interesting. Additionally, Chaos Space Marines are often used for their menacing and unpredictable nature in crossovers.
Ruby is often a popular choice. Her innocent yet powerful nature can be really interesting when placed in the Starcraft universe. Yang is also popular as her combat skills and fiery personality can create some intense storylines. Another popular character is Weiss, with her noble background and powerful Glyph abilities that can be reimagined in the context of Starcraft.
The IMC soldiers can also be great for crossovers. They have their own set of skills and motives. In a crossover with a stealth - based game universe, the IMC soldiers' combat tactics and equipment could add an element of intrigue.
Alya is also a great character to feature. Her intelligence and strategic thinking can be useful in different crossover scenarios. If crossed over with a science - fiction world, she could be involved in advanced technological research or battles against alien invaders.
Wonder Woman is an obvious choice as she is from Themyscira. She can be paired with characters from other universes like Superman for a DC crossover. In a crossover with the 'X - Men' universe, she could interact with Storm, two powerful female characters with different abilities. Another popular character would be Hippolyta. She could be involved in a crossover where she has to negotiate with leaders from other fictional kingdoms or planets.
Definitely Maurecia. She's got such a fun and unpredictable personality that she can bring a lot of energy to a crossover. Todd would also be great as he's often the 'normal' one in the Wayside chaos, so seeing him interact with characters from other worlds could be really interesting. And let's not forget Mrs. Jewls, who could use her wisdom and authority in a crossover situation to keep things in order or add some comical misunderstandings.
Master Chief is often a popular character. Given his significance in the Halo universe, it's natural for him to be a central figure in crossovers. He has the skills and determination to face the Flood threat. Another one could be the Arbiter. His unique perspective as a former Covenant and now an ally in the fight against common enemies makes him an interesting addition in fanfictions involving the Flood.
Master Chief is often a very popular character in Halo crossover fanfiction. His iconic status and combat skills make him a natural fit for crossovers. Writers like to put him in different scenarios and see how he reacts.
Definitely Master Chief. His stoic nature and combat skills would be really interesting to pair with Pokemon. He could be a silent but effective Pokemon trainer. Another would be Cortana. Her intelligence could be used to analyze Pokemon abilities and strategies. And of course, Pikachu would be a great character to include. It could be fun to see how it interacts with the Halo characters and technology.