William Penn
Penn (1644-1718) was a wealthy Englishman, the son of Sir William Penn, an English politican and admiral. The younger Penn became a member of The Religious Society of Friends (Quakers) in 1666 at age 22. He suffered imprisonment for being a Quaker. He wrote extensively about principles of democracy.
In 1681 Charles II granted a huge charter of land in North America to the younger Penn in settlement of a large debt the king owed to his father. Penn settled this new colony as a "Holy Experiment" providing religious toleration to many differrent groups including persecuted "Anabaptists" from continental Europe (the ancestors of today's Amish, Mennonites & Brethren).
Penn's writings on democratic government and the actual political institutions set up to govern the Pennsylvania province are often viewed as a model for the US form of government.
It is worth noting that Penn's prophetic insights did not extend to slave-holding. It is possible to view the slave quarters at Pennsbury, Penn's home in Bucks County, Pennsylvania.