In "To Kill a Mockingbird," Boo Radley figures as a person who fits the first line of a poem by William Wordsworth: "The World is too much with us." For, Boo who at one time in his youth rebelled against his fanatical father by fighting back, was severely punished. Now, misunderstood by the exterior world, he sequesters himself from the world in a manner not unlike Emily Dickinson. And, like Miss Dickinson, Boo is a sensitive and delicate soul, loving and kind albeit misunderstood.
It is significant that his name is "Boo," a name that reminds the reader of a ghost as his is a persona more like a spiritual element than a human. His small acts of love touch the hearts of the children, and he only "appears" when they are in danger. In the panoply of characters in Lee's novel, Boo represents the human spirit that must be protected and revered else it will die as it does in the other "spirit-like" character, Tom Robinson.
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Kind of person is a pretty vague question.
Important things to know about Arthur (Boo) Radley:
He is a recluse- made so by a restrictive father. He stabbed his father which resulted in him being jailed. Subsequently he only leaves his house at night.
The local children taunt Boo trying to make him come out of his home, however he often showed kindness to the kids by leaving trinkets and candy in a knot hole in a tree, and by repairing Jem's pants (torn on a fence when trying to get Boo out of the house).
Boo shows several examples of genuine kindness to Jem and Scout as well, covering Scout with a blanket after the fire and rescuing the children from Bob Ewell's attack.
Boo is a very analogous character to Tom Robinson in To Kill a Mockingbird. Both men are misunderstood and persecuted by many people in the town despite lack of cause. Thus both characters are representative of the mockingbird.