The person called the "Father of the Constitution" is James Madison. He is recognized for his crucial role in drafting and promoting the United States Constitution and the Bill of Rights. Madison helped organize the Constitutional Convention of 1787, authored the Virginia Plan which served as the basis for the convention's discussions, and was a key figure in the movement to ratify the Constitution. Additionally, he co-wrote The Federalist Papers, a series of influential essays advocating for the Constitution's ratification. Although Madison himself insisted the Constitution was the work of many, his extensive contributions earned him this title. He also served as the 4th president of the United States from 1809 to 1817.