Roger Williams was a 17th-century English theologian and founder of the colony of Rhode Island. He is best known for advocating for the separation of church and state and promoting religious freedom. Williams believed that individuals should have the right to practice their faith without interference from the government or other religious groups. In 1636, after being banished from the Massachusetts Bay Colony for his controversial views, Williams established Providence Plantations, which later became part of Rhode Island. His ideas laid the groundwork for the principles of tolerance and liberty that would influence the development of the United States.