The main character is Nightwing. In addition to him, there may be characters that are important to his backstory, like his family members if they play a role in his origin or his development as a hero. Also, there could be other superheroes or anti - heroes that he teams up with or has run - ins with in the 'Earth One' universe. Villains are also likely to be main characters in the sense that they drive the plot through their actions against Nightwing.
Barbara Gordon also plays a significant role in many of the stories. She's Batgirl, and she has a complex relationship with Nightwing. And then there's Alfred, who provides support to Nightwing just like he does for Batman.
It's mainly about the story of Nightwing in an 'Earth One' setting. It likely delves into his origin, his battles, and his relationships within that particular continuity of the DC Comics universe.
The Flash would surely be one of the main characters. There might also be his friends or family members who play important roles in his life and in the story. And of course, the villains that he has to face would also be key characters.
The main character is of course Bruce Wayne / Batman. And Alfred Pennyworth, who plays an important role in Bruce's life, is also a main character.
In the 'nightwing origin graphic novel', Dick Grayson is the central figure as he is the one whose origin is being told. Batman is a major character as he has a huge influence on Dick's life, from training him as Robin to their complex relationship later. There are also appearances by other members of the Bat - family like Barbara Gordon (Batgirl) who has her own interactions with Dick. And of course, the villains he faces during his early days are also part of the story.
The main characters would be Superman, of course. He's the central figure. Lois Lane is also a main character as she often has a significant role in Superman's story. His adoptive parents, Martha and Jonathan Kent, may also be important characters as they have influenced Superman's upbringing and values.
The main character is likely the Green Lantern himself. But there could also be other supporting characters like his friends, family, or maybe some other Lanterns.
Obviously, Wonder Woman herself is a main character. There may also be characters like Hippolyta, her mother, as the queen of the Amazons.
I don't know for sure. It could be some alternate versions of well - known superhero characters like Superman or Batman.
In the 'Batman Earth One' graphic novels, Bruce Wayne as Batman is at the center. He's a complex character dealing with his past trauma and trying to make Gotham a better place. Alfred is not just a butler but a father figure to Bruce, guiding him in many ways. Commissioner Gordon is a key figure in the fight against crime in Gotham. And we can't forget the villains. The Riddler, for example, is a main antagonist with his own motives and schemes that drive the story forward. There are also other characters like the members of the Gotham police force who play supporting roles in the overall narrative.