The members of the Young Guard as a whole are important characters. Each one has their own story and they all contribute to the overall narrative of resistance and struggle against the enemy.
I'm not aware of the exact main characters in 'the young imperial guard novel'. However, it's likely that among the main characters are some exceptional young guards who stand out. There could be a young guard with extraordinary combat skills or a very intelligent one who can solve complex problems within the imperial guard's scope of work. And perhaps there are also some important figures in the imperial court who interact with these young guards and play important roles in the story.
Dr. Frankenstein is obviously very important. He is the creator of the monster. The monster itself is also a crucial character. Then there are Dr. Frankenstein's assistants, who play a part in the creation process. And his family members are important too, as they are part of the background and his motivation in some ways.
Anne Frank is of course the most important character. She is the one writing the diary and through her eyes we see the whole story. Her father Otto Frank is also important. He is a source of support and stability in the family. Then there is her mother, Edith Frank, whose relationship with Anne is complex and adds depth to the story.
The most important character is Carmilla, the vampire. She has an alluring yet dangerous presence. The unnamed protagonist is also very important as we see the story through her eyes. There are other minor characters like the servants in the household where the story takes place. They help to create the atmosphere of the place, and sometimes their actions or words can give hints about what's going on with Carmilla.
Without having read the novel, we can only guess. There may be a group of friends as important characters. One might be the leader - type who is more outgoing and adventurous, leading the others into various situations. There could also be a shy character who grows and develops throughout the story. And perhaps there's a character with a troubled past who adds depth and complexity to the group dynamic.
The invisible man himself is of course very important. There's also Dr. Kemp, who has a significant role as he gets involved with the invisible man's story.
The most important character is Stephen Dedalus, the protagonist. He is the young man whose portrait we are following throughout the novel as he grows and changes.
The main character is surely the guard. There could be a villain or a group of antagonists that he has to face. Maybe there's also a mentor figure for the guard, someone who has taught him the skills he needs for his job and offers him advice throughout the story.
Mortarion is also a central character. His journey from a Primarch to a servant of Nurgle is a major part of the story. His decisions and actions shape the fate of the Death Guard as a whole.
Anne Frank is the most important character. It's her diary after all. She is a young, intelligent, and perceptive girl. Then there's her father, Otto Frank. He plays an important role in the family's hiding and survival. Her mother is also a character, although Anne often had a complex relationship with her.