There are likely to be his colleagues at work. They contribute to the corporate environment that he is a part of. They might be rivals in some ways or comrades in others, all of which shape his experiences at work. Also, his boss could be an important character as he is the one setting the rules and expectations in the corporate hierarchy.
The theme of identity is prominent. The protagonist is constantly grappling with who he really is within the context of his work, family, and society. There's also a theme related to post - war America. It shows how the post - war economic boom affected individuals, pushing them into a rat race where they had to sacrifice personal aspects of their lives to fit into the new corporate and consumerist culture.
The main character is the man in the gray flannel suit himself, of course. But there are also likely other characters like his family members, colleagues, and bosses.
The main theme could be seen as the conflict between personal desires and the expectations of society. In the 'the man in the gray flannel suit novel', the protagonist is constantly juggling his own dreams and the role he is supposed to play in the business - dominated society. He wants to provide for his family but also feels trapped by the monotony and shallowness of the corporate world. This struggle is at the heart of the novel's theme.
Agnes Grey herself is the most important character. She is the protagonist, a young governess whose experiences form the core of the story.
Obviously, Jean Grey herself is the most important character. She's the central figure around whom the whole story of the graphic novel revolves.
Obviously, the Grey Hulk himself is a crucial character. Then there's Bruce Banner, whose transformation into the Grey Hulk is central to the story. There might also be characters like Betty Ross who often has a role in Hulk - related stories and could be important in this graphic novel too.
Perhaps there is a family member, like a grandchild or a niece/nephew who has a special connection with Ptolemy Grey. This person could be important in terms of the emotional support they give or the way they help him face his last days. And there could be a doctor or a medical professional who is involved in his care.
I'm not sure specifically as I haven't read this particular 'To the Last Man' by Grey Novel. But typically in such a story, there could be a strong, determined male lead who is the one likely to be the last man. There might also be a female character who provides support or motivation to the male lead.
In the 'the grey man story', the Grey Man is the central character. Alongside him, there could be a group of skeptics who don't believe in his existence at first. As the story progresses, they become witnesses to the Grey Man's actions and start to believe. There might also be a character who is hunting the Grey Man, either out of fear or for some other ulterior motive.
The main character is of course the Grey Man. He's a highly skilled and mysterious operative.