Aaron Burr Jr. (February 6, 1756 September 14, 1836) was an American politician and lawyer who served as the third vice president of the United States from 1801 to 1805. Burr's legacy is defined by his famous personal conflict with Alexander Hamilton that culminated in Burr killing Hamilton in a duel in 1804, while Burr was vice president.

Burr was born to a prominent family in New Jersey. After studying theology at Princeton, he began his career as a lawyer before joining the Continental Army as an officer in the American Revolutionary War in 1775. After leaving military service in 1779, Burr practiced law in New York City, where he became a leading politician and helped form the new Jeffersonian Democratic-Republican Party. As a New York Assemblyman in 1785, Burr supported a bill to end slavery, despite having owned slaves himself.At age 26, Burr married Theodosia Bartow Prevost, who died in 1794 after twelve years of marriage. They had one daughter, Theodosia.

In 1791, Burr was elected to the U.S. Senate, where he served until 1797. Burr would later run as the Democratic-Republican vice-presidential candidate in the 1800 election. An unintentional electoral college tie between Burr and presidential candidate Thomas Jefferson resulted in the House of Representatives voting in Jefferson's favor, with Burr becoming Jefferson's vice president due to receiving the second-highest share of the votes. Although Burr maintained that he supported Jefferson, the president was highly suspicious of Burr, who was relegated to the sidelines of the administration during his vice presidency and not re-nominated as Jefferson's running mate in 1804.

During his last year as vice president, Burr engaged in the duel in which he fatally shot Hamilton, his political rival, near where Hamilton's son Philip Hamilton died three years prior. Although dueling was illegal, Burr was never tried, and all charges against him were eventually dropped. Nevertheless, Hamilton's death ended Burr's political career.

Burr traveled west to the American frontier, seeking new economic and political opportunities. His secretive activities led to his 1807 arrest in Alabama on charges of treason. He was brought to trial more than once for what became known as the Burr conspiracy, an alleged plot to create an independent country led by Burr, but was acquitted each time. With large debts and few influential friends, Burr left the United States to live as an expatriate in Europe. He returned in 1812 and resumed practicing law in New York City. Burr's brief second marriage resulted in divorce and further scandal. Handicapped by a stroke and financially ruined, Burr died at a boarding house in 1836.

The Burr–Hamilton duel took place in Weehawken, New Jersey, between Aaron Burr, the Vice President of the United States, and Alexander Hamilton, the first and former Secretary of the Treasury, on the morning of July 11, 1804. The duel was the culmination of a bitter rivalry that had developed between both men who had become high-profile politicians in postcolonial America. In the duel Burr fatally shot Hamilton, while Hamilton fired into a tree branch above and behind Burr's head. Hamilton was taken back across the Hudson River and died the following day in New York.The death of Hamilton led to the permanent weakening of the Federalist Party and its demise in American domestic politics. It also effectively ended the political career of Burr, who was vilified for shooting Hamilton; he never held another high office after his tenure of Vice President ended in 1805.