Darth Vader from the Star Wars Galactic Empire could be a great character in an empire crossover. His dark and powerful presence would add a lot of drama. Also, Emperor Palpatine. In a crossover with another empire, they could be the antagonists trying to take over the new empire. Another character could be Captain America from the Marvel universe. If you consider the United States in the Marvel world as an 'empire' of sorts in terms of power and influence, his sense of justice and leadership could be interesting when put against the values of another empire.
Captain America could be a great character to use. He was a WW2 soldier himself, so it would be easy to create a crossover where he meets other soldiers from different parts of the war or different universes. Another one could be Indiana Jones. His adventurous spirit combined with the skills of a WW2 soldier could make for an exciting crossover. Also, Sherlock Holmes could be used. The WW2 soldier's practical knowledge and Holmes' deductive reasoning could lead to some interesting storylines.
Cleopatra is another great character. Her beauty and intelligence made her a very influential figure. In a crossover, she could use her charm and wits to manipulate characters from different settings. Say, if it's a crossover with a superhero world, she might try to enlist the help of the superheroes for her own political gain.
The emperor or empress is often a central character. Their decisions and leadership shape the empire. Then there are the generals, like General Thrax in many stories. He's known for his military strategies and loyalty to the empire.
Darth Vader is often very popular. His iconic status in Star Wars makes him a natural fit in crossovers. Fans love to see how he would interact with new characters from other empires or universes, using his dark side powers and his menacing presence.
Well, the Sith Lords in general are popular in these crossovers. Their use of the dark side of the Force and their power - hungry nature can create some intense storylines. And from other universes, characters like Captain Kirk could be included. His exploration - based mindset would clash with the Empire's more controlling nature. It could lead to some great moments of conflict and cooperation as he tries to navigate the Empire's complex politics and power dynamics.
Harry Potter and Luna Lovegood from the 'Harry Potter' series could be great for this. Harry is always in the thick of the action, focused on fighting Voldemort, while Luna has her own unique and dreamy way of seeing the world. An 'unexpected love' story could be that Harry, who has always seen Luna as a bit of an oddball friend, suddenly realizes he has deeper feelings for her during a particularly difficult time at Hogwarts, like when they are all in hiding and she brings a sense of calm and new perspective to him.
Hermione Granger from the Harry Potter series could be an interesting character. Imagine if she was hypnotized to forget all her magical knowledge. Another could be Katniss Everdeen from The Hunger Games. Hypnotizing her to not be able to use her archery skills would create a whole new set of challenges for her.
Eren Yeager is often used. His complex character arc in the original 'Attack on Titan' makes him a great candidate for crossovers. He can bring his determination and his unique Titan - shifting abilities to different fictional universes. Another popular character is Levi Ackerman. His combat skills and no - nonsense attitude are very appealing in crossover scenarios. He could hold his own against characters from other universes.
Mobius 1 is a very popular character often used. Given his status as a highly skilled pilot in the ace combat series, he makes for an interesting addition in crossovers. Another one is Pixy, his complex character and his relationship with Mobius 1 can bring a lot of drama to the crossover stories.
The colonists from Rimworld are often used as main characters. Their diverse skills and backstories make them interesting to pair with characters from other universes. For example, a skilled medic colonist could interact with a healer from a magical world.