If Billy is the representative of good, at one with the universe, Claggart is the epitome of evil and resides on the periphery of order. The serpent in Billy's Eden, Claggart serves as both tempter and destroyer. Melville's comparisons of Claggart to Tecumseh, the Shawnee, treacherous enemy of the English colonists, to Titus Oates, diabolical plotter against Charles II, and to Ananias, shameless liar struck dead by God, clearly and concisely sum up his evil nature.
Melville uses more physical description in outlining this character than he used in that of Billy or Captain Vere. Claggart is in his mid thirties, somewhat thin and tall. His small and shapely hands attest to light labor. His most notable features are a cleanly chiseled chin and cunning violet eyes, which cut into lesser sailors with a schoolmarmish glare. As strolling disciplinarian, he sports a rattan as symbol of his police role. His curly black hair contrasts with pallid skin that resembles marble. Altogether, the effect suggests anemia or some other bodily abnormality. As he accuses Billy of sedition, the contrast heightens as Claggart's eyes shift in intensity from light to a muddy purple and resemble a menacing reptile or fish.
Claggart takes a satanic role in that he tempts Billy to commit the sin of rebellion. He deliberately moves into close range and fixes Billy with a calculated stare. Claggart is often connected with serpents, as in the moments after his death when his body sags in the captain's hands like the coils of a dead snake. The fact that Melville leaves Claggart's background a mystery reinforces the idea that the master-at-arms represents a lurking, mesmerizing evil.