Who is John Hale Finch?

John Hale Finch is Atticus's younger brother. He is ten years younger than Atticus, and we learn that Atticus lives frugally for a time so that he can help his brother get a start in life. Atticus "invests" in putting John—or "Jack," as he is called—through medical school so that he can establish himself as a doctor during a time when "cotton was not worth growing." After giving his younger brother his chance, Atticus can then live comfortably on his earnings as a lawyer.
We also learn that Jack, who is shorter than Atticus, becomes rich as a doctor, and that every Christmas he "yells across the street" for Miss Maudie to marry him, which she, of course, refuses to do. Jack himself jokes that he will never marry, because raising children is too difficult.
Scout and the rest of her family meet up with Jack every year at Christmas at Finch's Landing. Scout recounts a Christmas in which Uncle Jack spanks her for attacking Francis but then is remorseful when he learns from her that he should have listened to her side of the story. We find out from this incident that Jack and Atticus have a close, comfortable relationship. Scout learns about Atticus's child-rearing wisdom and Atticus's worries for them over the upcoming Robinson trial from overhearing the two brothers talk.

John Hale Finch is Atticus's younger brother in the novel To Kill a Mockingbird. John is referred to as Uncle Jack and is a well-educated, morally upright doctor. Uncle Jack lives in Nashville and visits his brother's family during Christmas time. Scout and Jem enjoy his presence, and he gives them both air rifles for Christmas. Uncle Jack is a humorous man who doesn't have any children of his own. Scout teaches her uncle a lesson in parenting after he unknowingly punishes her for defending Atticus. Uncle Jack jumps to conclusions and spanks Scout after she punches Francis in the face. When they return home from Finch's Landing, Scout tells Uncle Jack the reason why she hit Francis in the face. Uncle Jack immediately apologizes and is upset at himself for treating Scout unfairly. Later on that night, Scout overhears Uncle Jack talking to his brother about the upcoming trial.