William Penn was born in London. He studied briefly, was thrown in jail a few times for his religious beliefs and became a Quaker. He sailed to America, while still in his thirties, along with others searching for religious freedom.
By coincidence, he later received a large piece of land as repayment for a debt that King Charles II owed his father, Admiral William Penn. The King's charter named the piece of land Pennsylvania. He preferred the name Sylvania so that people didn't think he chose the name after himself.
He was a prolific writer and many of the ideas in Pennsylvania's constitution found their way into the US Constitution. Sylvania means 'forest land' in Latin.