Hint: He was also a co-author of The Federalist Papers.

James Madison is widely considered the "Father of the Constitution" due to his pivotal role in its drafting and ratification. As a delegate at the Constitutional Convention in 1787, Madison's contributions were instrumental in shaping the framework of the U.S. government. He authored the Virginia Plan, which proposed a strong national government with a system of checks and balances, and took detailed notes during the convention that provide a crucial historical record. Madison also co-authored The Federalist Papers, a series of essays advocating for the Constitution's adoption, and played a key role in drafting the Bill of Rights. His extensive efforts and influence in the Constitution's creation and promotion earned him this esteemed title.