Who is Mr. Underwood in the novel To Kill a Mockingbird?

Mr. Underwood is the owner, editor, and printer of The Maycomb Tribune, the town's newspaper. He works and lives in the Tribune office, which is located across from the courthouse, and spends his days at his linotype. He constantly refreshes himself with his ever-present gallon jug of cherry wine.
When a mob of men approaches the courthouse and demands that Atticus leave (he is sitting outside, protecting Tom Robinson), Mr. Underwood trains a double-barreled shotgun on the mob. Though Atticus doesn't realize it until the mob has dispersed, Mr. Underwood has him covered during the entire episode. However, Mr. Underwood, whose first name is Braxton Bragg (after a Confederate general), won't allow a black person to go near him. Despite Mr. Underwood's apparent racism, he writes an editorial in his paper after Tom Robinson is convicted of raping Mayella Ewell. He writes that it's a sin to kill people who are crippled or weak, much as it's a sin to shoot a songbird. Mr. Underwood is clearly committed to his own vision of justice and believes that the verdict in the Tom Robinson case is unjust. 

Braxton Bragg Underwood is the owner and editor of The Maycomb Tribune and is a close friend of Atticus Finch. Scout mentions that Mr. Underwood's days were spent on the linotype and that he always had a jug of cherry wine present. She also comments that Mr. Underwood rarely left his office because people brought him the news. In Chapter 15, Atticus is warned about the Old Sarum bunch and a few community members fear that they will attempt to cause havoc before the trial. As predicted, the Old Sarum bunch attempts to lynch Tom Robinson. Fortunately, Mr. Underwood witnesses the entire situation from his office window and is holding a double-barrel shotgun to cover Atticus the entire time. Following Tom Robinson's trial, Scout mentions that Mr. Underwood wrote an editorial that compared Tom's verdict to the "senseless slaughter of songbirds" (Lee 147). Although Mr. Underwood is a racist, he has a conscience and believes in justice. He disagrees with the jury's decision because he thinks that it is wrong to harm crippled, helpless individuals. Mr. Underwood's editorial gives additional insight into his moral character and depicts him as an empathetic individual.