Alexander Hamilton (January 11, 1755 or 1757 – July 12, 1804) was a Founding Father of the United States, chief of staff to General Washington, one of the most influential interpreters and promoters of the Constitution, the founder of the nation's financial system, and the founder of the first American political party.

As Secretary of the Treasury, Hamilton was the primary author of the economic policies of the George Washington administration, especially the funding of the state debts by the Federal government, the establishment of a national bank, a system of tariffs, and friendly trade relations with Britain. He became the leader of the Federalist Party, created largely in support of his views, and was opposed by the Democratic-Republican Party, led by Thomas Jefferson and James Madison.

Hamilton served in the American Revolutionary War. At the start of the war, he organized an artillery company and was chosen as its captain. He later became the senior aide-de-camp and confidant to General George Washington, the American commander-in-chief. He served again under Washington in the army raised to defeat the Whiskey Rebellion, a tax revolt of western farmers in 1794. In 1798, Hamilton called for mobilization against France after the XYZ Affair and secured an appointment as commander of a new army, which he trained for a war. However, the Quasi-War, although hard-fought at sea, was never officially declared. In the end, President John Adams found a diplomatic solution that avoided war.

Born out of wedlock and raised in the West Indies, Hamilton was effectively orphaned at about the age of 11. Recognized for his abilities and talent, he was sponsored by people from his community to go to the North American mainland for his education. He attended King's College (now Columbia University), in New York City. After the American Revolutionary War, Hamilton was elected to the Continental Congress from New York. He resigned to practice law and founded the Bank of New York.

Hamilton was among those dissatisfied with the Articles of Confederation—the first attempt at a national governing document—because it lacked an executive, courts, and taxing powers. He led the Annapolis Convention, which successfully influenced Congress to issue a call for the Philadelphia Convention in order to create a new constitution. He was an active participant at Philadelphia and helped achieve ratification by writing 51 of the 85 installments of the Federalist Papers, which supported the new constitution and to this day is the single most important source for Constitutional interpretation.

In the new government under President George Washington, Hamilton was appointed the Secretary of the Treasury. An admirer of British political systems, Hamilton was a nationalist who emphasized strong central government and successfully argued that the implied powers of the Constitution could be used to fund the national debt, assume state debts, and create the government-owned Bank of the United States. These programs were funded primarily by a tariff on imports and later also by a highly controversial excise tax on whiskey.

Embarrassed when an extra-marital affair from his past became public, Hamilton resigned from office in 1795 and returned to the practice of law in New York. He kept his hand in politics and was a powerful influence on the cabinet of President Adams (1797–1801). Hamilton's opposition to Adams' re-election helped cause his defeat in the 1800 election. When in the same contest Thomas Jefferson and Aaron Burr tied for the presidency in the electoral college, Hamilton helped defeat Burr, whom he found unprincipled, and elect Jefferson despite philosophical differences. After failing to support Adams, the Federalist candidate, Hamilton lost some national prominence within the party. Vice President Burr later ran for governor in New York State, but Hamilton's influence in his home state was strong enough to prevent a Burr victory. Taking offense at some of Hamilton's comments, Burr challenged him to a duel and mortally wounded Hamilton, who died within days.