Nathan Radley is the brother of the mysterious Boo Radley in Harper Lee's novel To Kill a Mockingbird. After Boo's father dies, Nathan takes over as head of the household and, presumably, as the protector of Boo. Very little is known about "Mr. Nathan," and he is only mentioned a few times in the story. His most prominent appearance comes when he cements up the knothole in the tree--the secret hiding place where Jem and Scout communicate with Boo. He also fires a shotgun at the kids one night, and helps out a bit on the night of the big fire. He is a minor character, serving only as a connection to Boo.