Dragons could also be main antagonists. Harry is used to dealing with magical creatures at Hogwarts, but dragons in Skyrim are much more powerful and unpredictable. Their attacks on settlements and their hoarding of treasure could make them a constant threat to Harry and the people he wants to protect.
The Dark Brotherhood or some powerful necromancers in Skyrim could be antagonists. The Dark Brotherhood's assassinations and the necromancers' dark magic go against Harry's moral code. He would have to use his skills and magic to stop their evil deeds, which could lead to some intense battles and moral dilemmas.
The Thalmor could be great antagonists. Their strict control over magic and their anti - human beliefs could put them at odds with Harry. They might see his different form of magic as a threat to their power in Skyrim.
One possible antagonist could be a corrupt wizard in a high - ranking position in the Ministry of Magic's financial department. This wizard might be trying to cover up his misdeeds and would see Harry as a threat to his scheme.
Scarecrow could also be a main antagonist. His fear - inducing toxins could be a real problem for Harry. Harry would have to use his magic to counter the effects of the fear toxin and also figure out a way to stop Scarecrow from spreading it all over Gotham.
It could be the other Titans who don't want a half - wizard, half - Titan like Harry to exist. They might see him as a threat to their pure Titan bloodlines or their power structure.
The Death Eaters could still be the main antagonists. They might see Fenrir's new alliance with Harry as a threat. Since they once used Fenrir for their dark deeds, they don't want him to turn good and expose their secrets.
There could also be a trainer who is jealous of Harry's unique abilities, being reborn from the Harry Potter world. This trainer might try to undermine Harry at every turn, stealing his Pokemon or sabotaging his battles, much like Draco Malfoy was often in conflict with Harry in the original Harry Potter series.
It could be a powerful dark wizard who has a grudge against the goblins and wants to destroy Gringotts. This wizard might have been wronged by the goblins in the past, and now he's seeking revenge by trying to bring down the bank. He could be using his own army of dark creatures to attack Gringotts.
The Death Eaters would be obvious antagonists as they are in the original Harry Potter series. But also, there could be a group of shadowy figures from Nightwing's world who oppose the idea of a wizard - Nightwing hybrid. They see Harry as an abomination and try to eliminate him before he can fully realize his powers.
In this fanfiction, a main antagonist could be a powerful dark witch who has the ability to summon and control hordes of monsters. She believes that the wizarding world has become too soft and that only through chaos and fear brought by the monsters can it be purified. Harry, as the Monster Slayer, is her biggest obstacle. Another antagonist could be a group of Death Eaters who have discovered a way to use monsters as weapons in the post - Voldemort era. They want to continue the dark legacy and see Harry as the one who will always stand in their way. Also, a mysterious figure from the past, a forgotten dark wizard who has been locked away for centuries but is now free and is using monsters to exact his revenge on the modern wizarding world.
In addition to Voldemort, there might be dark wizards who are jealous of Harry's new Hanyou powers. They could team up with some of the anti - Harry Hanyous to create a powerful alliance against him. This would force Harry to make some difficult choices about who to trust and how to fight back.
One possible main antagonist could be an Atlantean sorcerer who is jealous of Harry's growing influence and power in Atlantis. This sorcerer might have his own plans to rule Atlantis and sees Harry as a threat. Another could be a group of traditionalist Atlanteans who oppose any foreign influence, like Harry's, and they try to undermine his attempts to bring new ideas and magic from Hogwarts.