James Madison is the founding father known for his key role in drafting the U.S. Constitution. Often referred to as the "Father of the Constitution," Madison played an instrumental role in shaping the document during the Constitutional Convention of 1787. He advocated for a strong central government and contributed to the creation of the system of checks and balances that defines the U.S. political structure. Additionally, Madison was a co-author of The Federalist Papers, which promoted the ratification of the Constitution. He later served as the fourth President of the United States and was a significant figure in early American governance.