Well, from the title, one main character is likely the penguin. And since death is in the title too, death could be another main character, maybe personified as some kind of entity.
The main characters are usually the penguin avatars. There could be a brave little penguin who is always ready for an adventure, or a friendly penguin who loves to make new friends.
Since it's a graphic novel, the visuals would play a huge role. The art style could be used to depict death in a unique way, perhaps as a shadowy figure or a force of nature. The penguin, being the main character, might have its own personality. It could be a curious penguin that stumbles upon death's realm. Or it could be a penguin that is already marked for death and is trying to escape its fate, leading to an adventure full of challenges and self - discovery.
I'm not sure as there's not enough info given. It could be anyone from fierce warriors to superpowered beings.
Since I don't have detailed knowledge of 'life and death graphic novel', it's hard to say for sure. However, in many such graphic novels, there could be a hero - like character who is trying to overcome the challenges related to life and death. There might also be a villain or antagonist who either causes or exacerbates the life - threatening situations. And there could be supporting characters like friends or family members of the main character who play important roles in the story.
It's possible that the main character is a journalist who is investigating the death ray. Along the way, they meet a mysterious figure who has inside knowledge about the death ray's origin and capabilities. There could also be a military general who is either trying to obtain the death ray for national security or trying to prevent it from falling into the wrong hands.
Perhaps there is a young protagonist, a curious and brave individual who stumbles upon the secret of the death ray. There could also be an antagonist, someone with malicious intent who wants to use the death ray for their own gain. And then there might be supporting characters like the protagonist's friends or family who get involved in the events related to the death ray.
The main character is Death Jr. of course. There might also be other characters like his friends or family members, though I'm not sure exactly who without more in - depth knowledge of the specific graphic novel.
In the 'Death of Superman Graphic Novel', Superman is at the core. His struggle against Doomsday is the main plot. Doomsday is this terrifying and extremely powerful being that is a major part of the story. Lois Lane is an essential character. She has an emotional connection to Superman, and her presence adds depth to the story. The other characters include the Justice League. They try to help Superman fight Doomsday but ultimately fail. Their reactions and how they deal with the aftermath of Superman's death are also important parts of the story.
The two main characters are Light Yagami and L. Light is a brilliant student who discovers the Death Note and starts using it to kill criminals, believing he can create a new world order. L, on the other hand, is a world - famous detective who is determined to catch Kira (Light).
There might be a teacher - like figure in the 'death class graphic novel'. This character could be guiding the students through their exploration of death. And there could be some students who stand out, for example, one who is very resistant to the idea of death and another who is overly curious. These different personalities would create interesting dynamics within the story.