Leviathan is the title of Thomas Hobbes' 1651 work on the social contract and the origins of creation of an ideal state, and his proper name for the Commonwealth.
You may read more about Leviathan here :- http://en.wikipedia.org/wiki/Leviathan
Thomas Hobbes (5 April 1588 – 4 December 1679) was an English philosopher, remembered today for his work on political philosophy. His 1651 book Leviathan established the foundation for most of Western political philosophy from the perspective of social contract theory.
Hobbes also contributed to a diverse array of fields, including history, geometry, physics of gases, theology, ethics, general philosophy, and political science. His account of human nature as self-interested cooperation has proved to be an enduring theory in the field of philosophical anthropology. He was one of the main philosophers who founded materialism.....
You may read more about Thomas Hobbes here :- http://en.wikipedia.org/wiki/Thomas_Hobbes