I'm not entirely sure without having read it thoroughly, but there's likely to be the character associated with the black phone. Maybe it's a victim or someone who has a special connection to the strange events related to the phone.
In 'The Black Phone and Other Stories', we might expect to find a range of characters. There could be a group of children, as often in horror stories involving the unknown, children are the ones who first encounter the strange phenomena. One of them could be the main character who has to deal with the enigma of the black phone. There could also be adults, like parents or authority figures, who either don't believe the children at first or are also affected by the events in different ways. Their reactions and interactions would add depth to the story and help to build the overall atmosphere of horror and mystery.
There are also the victims in the stories. Although they may not be as fully developed as the main characters, they play an important role in highlighting the horror of the events. In 'The Black Cat', the wife of the narrator is a victim of his rage and insanity. Their presence shows the consequences of the main characters' actions.
I'm not entirely sure, but there could be a person who discovers the black phone. This character would be central as they start to uncover the secrets related to it.
There is the narrator in many of the stories. His perspective is crucial as he guides us through the strange events. Also, in the story of 'The Aleph' itself, Carlos Argentino Daneri is a notable character. He is the owner of the house where the aleph is supposedly located.
In 'The Lottery', Tessie Hutchinson is a notable character. She becomes the victim of the lottery, and her protests at the end highlight the horror of the situation.
The old man in the story by the river is also a character that stands out. He has a lot of wisdom that he imparts, but also a sad backstory that is gradually revealed throughout the story. His presence in the story adds depth and a sense of melancholy as he reflects on his life and the changes in the world around him.
In 'Games at Twilight', Ravi is a notable character. He is a child who experiences a range of emotions during the game. His eagerness to win and then his sense of disappointment and isolation when things don't go as planned make him a complex character.
In 'The Overcoat', Akaky Akakievich is a very notable character. He is a low - ranking clerk who is meek and mild - mannered. His life revolves around his work of copying documents, and his new overcoat becomes a symbol of his hopes and dreams.
Well, since it's a friend of Kafka, that friend would be a notable character. Maybe it's someone who has a deep understanding of Kafka or is influenced by him in some way. There could also be other characters who are in contrast to this friend, like those who don't understand Kafka's ideas at all.
Well, the unnamed protagonist in 'The Call of Cthulhu' is quite important. He's the one who stumbles upon the dark secrets and the cult that worships Cthulhu. There are also the cult members themselves. They play a significant role as they are the ones trying to bring about the return of Cthulhu. And Cthulhu, that huge, tentacled, and indescribably hideous entity, is a central character in a sense. It represents the ultimate cosmic horror that the whole story revolves around.
I'm not sure specifically as I haven't read it in detail, but there might be a protagonist who is at the center of the story about 'half a life'. This character could be someone who has experienced a major change or turning point in their life.