Leviathan appears as a normal whale, but with, apparently, no eyes. It's skin is a dark shade of blue on the top, and a lighter shade on its underside. However, towards the end of Finn's dream, Leviathan appears purple. Leviathan also has sharp teeth, unlike some whales, allowing it to eat Finn easily.
- Leviathan's name was most likely inspired by the biblical creature of the same name.