James Madison (March 16, 1751 – June 28, 1836) was an American statesman, diplomat, and Founding Father who served as the fourth president of the United States from 1809 to 1817. Madison was popularly acclaimed the "Father of the Constitution" for his pivotal role in drafting and promoting the Constitution of the United States and the Bill of Rights.

Madison was born into a prominent slave-owning planter family in Virginia. He was a member of the Virginia House of Delegates and the Continental Congress during and after the American Revolutionary War. Dissatisfied with the weak national government established by the Articles of Confederation, he helped organize the Constitutional Convention, which produced a new constitution designed to strengthen republican government against democratic assembly. Madison's Virginia Plan was the basis for the convention's deliberations. He became one of the leaders in the movement to ratify the Constitution and joined Alexander Hamilton and John Jay in writing The Federalist Papers, a series of pro-ratification essays that remains prominent among works of political science in American history. Madison emerged as an important leader in the House of Representatives and was a close adviser to President George Washington. During the early 1790s, Madison opposed the economic program and the accompanying centralization of power favored by Secretary of the Treasury Hamilton. Alongside Thomas Jefferson, he organized the Democratic–Republican Party in opposition to Hamilton's Federalist Party. Madison served as Jefferson's Secretary of State from 1801 to 1809, during which time Jefferson made the Louisiana Purchase.