Since I haven't read the 'ambassadors of death novel', I can't say for sure who the main characters are.
Not having read the 'ambassadors of death novel', it's impossible to accurately name the main characters. However, it's likely that there are characters who are on a mission to deal with the ambassadors of death. There might be a scientist who is trying to understand the nature of these ambassadors, a military leader who is formulating a plan to combat them, or an ordinary person who gets caught up in the events and becomes an unlikely hero in the face of the threat posed by the ambassadors of death.
The main characters include Lambert Strether, who is central to the story as he navigates his role as an 'ambassador' of sorts. Chad Newsome, the young man he is sent to retrieve, and there are other characters like Madame de Vionnet who plays a significant role in Chad's life in Paris and also in Strether's experiences there.
I'm not sure specifically as I haven't read it. But generally, it might be about some characters who are ambassadors of death. Maybe they are involved in some sort of apocalyptic or dangerous events, or they could be some sort of otherworldly beings causing death in a particular story world.
I'm not sure specifically as I haven't read the 'death notice novel' in detail. But usually in such novels, there is a protagonist who is likely to be someone involved in solving the mystery or facing the challenges related to the 'death notice'.
The main characters could include the god of death, of course. There might be a human character who has a special connection to the god of death, perhaps a seer or someone with a rare gift. And there could be a council of deities that the god of death has to interact with, whether they are allies or foes. These various characters would each contribute to the overall plot and theme of the novel.
Since I'm not familiar with the book, it's hard to say who the main characters are. But they could be humans who are involved in the robotics industry, like engineers or scientists. Or perhaps there are some special robots that are the focus, such as a robot detective or a powerful combat robot.
Since I don't know the specific 'death watch novel', I can't say for sure. But they could be the people on the death watch, like a doctor, a family member, or a professional caregiver.
Since I don't know the specific 'death crone novel', I can't say for sure. But likely, the death crone herself would be a main character. There might also be characters whose lives she affects, like a young hero who tries to stop her evil deeds if she's a villain, or a person seeking her wisdom if she has a more ambiguous role.
The main character is Gustav von Aschenbach, an aging writer. And then there's Tadzio, the beautiful young boy who becomes the object of Aschenbach's obsession.
I'm not entirely sure about all the main characters in the 'death stranding novel' since I haven't read it fully. But based on the game, in addition to Sam, characters like Mama, who has a special connection to a BT, could be important in the novel. There may also be new characters introduced in the novel that play crucial roles in the story, perhaps some leaders of the different settlements or people who have special abilities related to the chiral network.
I don't know specifically as I haven't read it, but there's likely to be the adept themselves (even though they die), and perhaps people close to the adept like friends, family, or colleagues.