Who would be the main antagonist in a Harry Potter x Kara Thrace fanfiction?

One possible plot could be that Kara Thrace somehow ends up in the wizarding world of Harry Potter. Maybe she crashes her Viper into a magical portal. She then teams up with Harry Potter and his friends. With her combat skills and fearless nature, she helps them in their fight against Voldemort. For example, she could teach them some advanced combat maneuvers from her military training.

Voldemort could easily be the main antagonist. His goal of taking over the wizarding world and his use of dark magic would put him in direct conflict with Boromir and Harry. Boromir's sense of justice would not allow Voldemort's tyranny to stand, and Harry has his own vendetta against the Dark Lord.

Another option is a powerful dark wizard from the past in the wizarding world who has been banished to the underworld. He wants revenge on the wizarding world and plans to use Hades' power to break free and wreak havoc. Harry Potter must then face this resurrected dark wizard and prevent him from using the underworld as a base for his revenge.

The main antagonist could be a dark wizard who has mastered water - based magic and has made a pact with a powerful sea monster. This dark wizard wants to rule both the wizarding world and the underwater world. He sees Harry Potter as a threat to his plans in the wizarding world and Aquaman as a hindrance in the underwater realm.

There could be a new character created specifically for the fanfic. A dark wizard who has been observing the wizarding world from the shadows and sees Hisoka's arrival as an opportunity. This new antagonist could try to use Hisoka to achieve his own evil goals, like opening a portal to a dark dimension or stealing all the magic in the world. When Hisoka realizes he's being used, he would turn against this new antagonist, and Harry Potter and his friends would join him in the fight.

It could be Voldemort still. Imagine Ares coming into the Harry Potter world, and Voldemort seeing this as a threat to his own power. He would try to either eliminate Ares or use him for his own dark purposes. Ares, on the other hand, may not take kindly to Voldemort's evil ways and so they become enemies, with Harry in the middle trying to defeat Voldemort while also keeping Ares in check.

The mummy itself could be the main antagonist. It could be a mummy that was once an evil sorcerer in ancient Egypt, and now that it has been awakened, it wants to spread its dark magic and rule over both the Muggle and wizarding worlds.

Obviously, Slenderman could be the main antagonist. His spooky nature and his ability to cause fear and disappearances would make him a perfect fit for the role. He could be trying to spread his influence over the wizarding world, which would put him in direct conflict with Harry and his friends.

It could be Voldemort and Loki. Voldemort, being the main villain in the Harry Potter series, is power - hungry and wants to rule the wizarding world. Loki, from the God of Thunder universe, is known for his trickery and his own desires for power. They could team up, thinking that they can use each other to achieve their goals. Voldemort could be interested in Loki's ability to deceive and Loki could see the potential in Voldemort's dark magic. They would be a formidable pair against Harry Potter and Thor.

It could be a dark wizard who has somehow learned about the existence of the Mikaelsons and wants to use their power to take over the wizarding world. He might be jealous of their unique abilities and see them as a means to gain ultimate power, so he targets Hope, and Harry has to protect her and stop this dark wizard.