U Mobi Diku Melvil se osvrće na zlo, otelovljeno u dva glavna lika: s jedne strane je kit, koji predstavlja zlo bez osećanja pošto uništava sve na šta naiđe, a s druge je kapetan Ahab, koji predstavlja uporno zlo, pošto ga njegova lična mržnja i glad za osvetom teraju da goni kita iako time izlaže opasnosti živote svojih ljudi.   In Moby Dick, Melville reflects on evil as represented in the principal characters: on the one hand the whale, which represents senseless evil, as it destroys everything it comes across; on the other hand Captain Ahab, who represents a stubborn evil, as his personal hatered and desire for revenge makes him hunt the whale down, even though he is putting his men's lives at risk.