Not having full details about the 'the girl in the wall story', we can assume the girl is a main character. There could be other supporting characters. For instance, if it's a mystery - type story, there might be a detective - like figure trying to solve the mystery of the girl in the wall. Or if it's a fantasy story, there could be magical creatures that are either helping or hindering the girl's situation in relation to the wall.
As the details of the 'girl in the wall story' are not clear, it's difficult to determine the main character precisely. However, if it follows the common idea of a girl being in a wall, she would be the main focus. She could be a young girl with a unique backstory, like she was put there by some villain, or she ended up there by accident while exploring an old building. The story would likely revolve around her experiences and how she either gets out or what her purpose is while being in that situation.
Obviously, the two main characters are the Wall Street bull and the little girl.
Since I don't know the exact 'the wall short story', it's hard to say. But often in stories about a wall, there could be a builder of the wall, someone who is trapped by the wall, or a person who is trying to break the wall down.
Since I don't know the exact 'the long wall story', it's hard to say who the main characters are. They could be the builders of the wall, if it's a story about construction. Or perhaps people who live near the wall and are affected by it.
I'm not sure who the main characters are in the 'War of the Wall Story' as I don't have more context. It could be leaders of the opposing sides in the war over the wall, or ordinary people who are affected by the wall and take a stand.
Without reading the 'the hole in the wall short story', it's hard to say for sure. But it could be a group of friends who find the hole in the wall together. One of them could be the brave one who first dares to look through or enter the hole. Another character might be the cautious one who tries to stop the others at first but then gets drawn into the mystery. And there could be a character who has some knowledge about the wall's history and the origin of the hole, which adds depth to the story.
Not having read 'the man in the wall short story', it's hard to be definite. However, we know there's the man in the wall. There may be characters like a child who discovers the man in the wall and then tells their parents, which could lead to a series of events. Or there could be an old wise person in the story who has some knowledge about the wall and the man, and tries to offer advice or help regarding the situation.
Typically, the main character is the one who discovers the door in the wall. But without more specific knowledge of the particular version of the story, it's hard to name others precisely.
There could be a group of young people in the story who see the wall as something that limits their freedom and want to change it. And on the other side, there might be some older, more traditional people who see the wall as a necessary part of their community's history and protection.
I'm not sure exactly without reading it again, but there could be an artist and some local residents.