The frontspiece to Leviathan is almost as famous as Hobbes' arguments within. The name "Leviathan" is a reference to a sea monster that is mentioned in the Old Testament (Psalms 74:13-14; Job 41; Isaiah 27:1). There are varying interpretations of what precisely the biblical "leviathan" is a metaphor for (if anything), but prominent among these theories is the notion that the leviathan represents some force of evil or product of hell. St. Thomas Aquinas used the term leviathan to refer to a demon of envy that is among the first to punish sinners when they enter hell. Milton, in Paradise Lost uses "leviathan" to refer to the size and scope of Satan. (Some even view Paradise Lost as a critique of Leviathan.
Regardless of how Biblical scholars or other writers used the word "leviathan," Hobbes uses it in a more benign way to describe the all-encompassing, all-powerful state. The frontspiece of the book has a picture of this "leviathan" towering over the state, and upon closer inspection of this image, one can see precisely what Hobbes' leviathan was meant to be. The leviathan's body is made up of individual people, all of whom are angled so that they are looking upward at the leviathan's head. In other words, the leviathan or sovereign is not just an absolute monarch who rules over the subjects by virtue of a divine right to rule, but rather, the sovereign rules through the consent of all subjects. The picture of the leviathan shows the paradoxical nature of Hobbes' philosophy: the state as a democratic autocracy.
