Another character that could be important is Dumbledore, even if he's dead in the original series. In fanfiction, he could appear as a ghostly mentor to Harry, guiding him on his path as the Overlord. And then there are the villains or antagonists, like Voldemort's followers who might oppose Harry's new regime.
Some fanfictions may introduce new characters that are unique to the 'Harry Overlord' concept. These could be powerful wizards or witches from other parts of the world who come to either support or challenge Harry's rise to power. They add new dynamics and storylines to the fanfiction.
One possible main character could be a vampire hunter. This hunter might initially be after the forgotten overlord but then realizes that there are greater threats in the vampire world and teams up with the overlord. Another character could be a witch who has knowledge about the spell that made the overlord forgotten and helps him to break it.
Albedo is also a very important character. She is deeply in love with Ainz and is one of the guardians of the Great Tomb of Nazarick. She is extremely powerful and plays a crucial role in Ainz's plans and the protection of Nazarick.
The main character is Momonga. He is a very powerful being in the story. His transformation and growth throughout the novels are central to the plot.
Hermione Granger and Albedo could also be characters that interact. Hermione is known for her intelligence and thirst for knowledge. Albedo is extremely intelligent as well in matters of strategy and magic in the Overlord world. They could exchange knowledge about their respective magic systems, like Hermione explaining the theory behind Transfiguration to Albedo.
Ainz Ooal Gown is the main character. He is a powerful undead wizard who was once a normal gamer in the real world but now finds himself in a new world where he has to use his wits and powers to survive and rule.
The main character is Momonga, also known as Ainz Ooal Gown. His subordinates like Albedo, Sebas Tian, and Shalltear Bloodfallen are also important characters in the story.
There are also characters like Demiurge. He is a demon - type character and one of the smartest and most devious in Ainz's service. He is often involved in planning and strategizing for Ainz. These main characters, along with many others, contribute to the rich tapestry of the Overlord light novels.
Momonga is the main character. He is a powerful wizard in the game world where he gets stuck. Albedo is another important character, a succubus - like being who is extremely loyal to Momonga. Then there's Sebas Tian, a butler - type character with high combat abilities. These characters play crucial roles in driving the story forward.
Ainz Ooal Gown is the main character. He is an undead sorcerer who was transported to the new world along with the Great Tomb of Nazarick.
Ainz Ooal Gown is the main character. He is the powerful overlord in the story.