Who is Boo Radley from "To Kill A Mockingbird"?

He is a neighbor of Jem and Scout. The children have a very cruel curiosity about who Boo actually is. He keeps pretty much to himself which only makes them more curious. Then Scout and Jem get little toys from Boo, which softens their opinion of him considerably, especially Scott who, along with Boo, is the very essence of innocence in American Literature. She, of the three children, has the most knowing heart, and Atticus takes great pains to guide that heart.

Boo later turns up to rescue Scout as she is on her way home from a school activity. Boo has to murder someone to save and because he is one of the Mockingbirds, the sheriff decides that it would be inhumane to arrest him. Tom Ewall was a very evil being and the sheriff decides that rather than push the law, he will push common sense. "Let the dead bury the dead." is what he says about that horrible evening.

Town outcast whom children constantly try to see.