The dragon in J.R.R. Tolkien's novel 'The Hobbit' is named Smaug, a five-letter word that can be found in the crossword puzzle. Smaug is a powerful and fearsome dragon who lives in the Lonely Mountain and guards a vast hoard of treasure. He is described as having red eyes, a long neck, and wings that allow him to fly. Smaug is the main antagonist of the novel and is ultimately defeated by the protagonist, Bilbo Baggins.