Who is Boss (Bodymaster) McGinty in Sir Arthur Conan Doyle's, The Valley of Fear?

Boss McGinty is one of the novel's main antagonists. He is the leader of “the Scowrers," and he is described as cruel, fearsome, and unrelenting. McGinty is unchallenged as the "lord" of Vermissa Valley (Valley of Fear), which he rules with an iron fist, crushing those who get in his way.