Supergirl herself is of course the most important character. Then there's often Superman, her cousin, who can play a significant role in her story, either as a mentor or as someone she compares herself to. Also, her friends on Earth, like those she meets at school or in her daily life, are important as they represent the normal part of her world that she tries to protect.
Supergirl is the key character. But there are likely villains too. Maybe some powerful alien antagonists who want to take over Earth or harm Supergirl. Her adoptive parents, if they are part of the story, are also important as they help shape her view of Earth and humanity. And there could be other superheroes or sidekicks who team up with her from time to time.
Obviously, Supergirl is the main character. She is a powerful Kryptonian with abilities like super strength, flight, and heat vision.
John Constantine is the most important character, of course. He's a complex anti - hero. He has a rough exterior, often smoking and drinking, but is extremely intelligent when it comes to dealing with the occult. Then there are the various demons and devils he has to face, like Nergal. Nergal is a powerful demon that often causes trouble for Constantine.
Obviously, Deathlok himself is the most important character. He is the central figure around which the story revolves. There may also be his creators or the people who turned him into a cyborg, who are important as they set the whole story in motion.
The protagonist is surely an important character. He is the one who drives the story forward with his decision to go into the wild. There may also be characters from his past life, like his family members, who play a role in shaping his journey.
Sif is an important female character in Thor's life. She is a skilled warrior and has a complex relationship with Thor. The Enchantress is a villainous character who often tries to manipulate Thor for her own gain. Her magic and seductive ways add a different dynamic to the story.
Batman is obviously an important character. Also, the villains like the Joker are likely to be important in this graphic novel.
Obviously, Napoleon himself is a very important character. His character would be central to the plot, showing his actions, decisions, and personality. There might also be his generals, like Murat or Ney, who played important roles in his military campaigns.
Then there's Ajak. Ajak serves as a sort of leader or guide among the Eternals. He has a deep understanding of their history and purpose. His wisdom is relied upon by the others when they face difficult choices or need to understand their place in the grand scheme of things.
In 'deathstroke graphic novel', Deathstroke is central. But his family members can also be very important characters. For example, his children might play a role in his story, either as a source of motivation or as a complication. Also, his handlers or employers, if he has any, could be important as they give him missions and influence his actions.
Batwoman herself, Kate Kane, is of course very important. And there are her allies like Luke Fox.