The characters of Robert Frost's "Out, Out—" can be seen as archetypal or typical stock characters that we might encounter in literary works or other forms of art. The characters are the boy, his sister, the saw, the doctor, and "they."

The Boy

The poem tells the story of a boy whose hand is cut off by a saw when he is chopping wood. The boy is portrayed as an innocent young man who is doing his chores for the family when this tragedy befalls him. Frost reveals the boy’s shock when the saw cuts him—the first thing he does is laugh. Then, as he realizes the truth, he thinks of his life and begs his sister to protect him from the doctor. "Don’t let him cut my hand off." Next, we witness the boy’s terror as the doctor gives him ether, and "his pulse took fright." Finally, the boy succumbs to his fear, and the doctor cannot detect his heartbeat. The reader is left in a state of shock as the innocent boy gives
his life instead of his hand.

The Saw

The saw is personified as something that intentionally "Leaped out at the boy's hand." We can view the saw as the villain that strikes the innocent victim. Therefore, the boy and the saw represent the typical struggle between good and evil. Frost seems to be saying that sometimes bad things happen to good people, and there is no good explanation. The speaker states that the saw seems to "know what supper meant" because it takes the opportunity to strike at the boy when he is just about to stop work to eat his meal. However, Frost gives the villain a way out: the speaker says the boy "must have given the hand," which indicates the suddenness of the
tragedy.

The Sister

The boy's sister is present when the tragedy happens, as she is the one who calls him in for supper. Here, she can be seen as an innocent who is unable to help her brother as she watches the saw jump at his hand. There is no indication of her reaction, only the boy’s pleading, so we can assume that the tragedy takes place so quickly that she has no time to react.

"They"

The sister’s role changes at the end of the poem as she becomes part of "they" who watch the young man die. It is unclear how many people are in the house, but it's understood that the word "they" refers to the family that "turned to their affairs" after the boy dies. We might consider that we, the readers, are also part of "they," since we also grieve with the boy, yet we move on after reading the poem.

The Doctor

Finally, we see the doctor, who is an archetypical wise character. The boy and his family turn to the doctor to help, but events are out of his hands, as the saw has done too much damage. The healer is unable to save the boy.