John Claggart is a fictional character from Herman Melville's novella, "Billy Budd, Sailor." He serves as the master-at-arms on the British warship HMS Bellipotent. Claggart is depicted as a complex antagonist, characterized by his jealousy and malice towards the young sailor, Billy Budd. Claggart's actions are driven by an inexplicable hatred for Billy, who represents innocence and goodness. This conflict culminates in a tragic confrontation, highlighting themes of good versus evil and the nature of human morality. Claggart's role is essential in exploring the darker aspects of human nature within the story.