Henry Clay (April 12, 1777 – June 29, 1852) was an American lawyer and statesman who represented Kentucky in both the U.S. Senate and House of Representatives. He was the seventh House speaker as well as the ninth secretary of state. Clay unsuccessfully ran for president in the 1824, 1832, and 1844 elections. He helped found both the National Republican Party and the Whig Party. For his role in defusing sectional crises, he earned the appellation of the "Great Compromiser" and was part of the "Great Triumvirate" of Congressmen, alongside fellow Whig Daniel Webster and Democrat John C. Calhoun.

Clay was born in Hanover County, Virginia, in 1777, and began his legal career in Lexington, Kentucky, in 1797. As a member of the Democratic-Republican Party, he won election to the Kentucky state legislature in 1803 and to the U.S. House of Representatives in 1810. Clay was chosen as Speaker of the House in early 1811 and, along with President James Madison, led the United States into the War of 1812 against Great Britain. In 1814, he helped negotiate the Treaty of Ghent, which brought an end to the War of 1812, and then after the war, Clay returned to his position as Speaker of the House and developed the American System, which called for federal infrastructure investments, support for the national bank, and high protective tariff rates. During 1820, Clay helped bring an end to a sectional crisis over slavery for many years by leading the passage of the Missouri Compromise. He finished with the fourth-most electoral votes in the multi-candidate 1824–1825 presidential election and used his position as speaker to help John Quincy Adams win the contingent election held to select the president. President Adams then appointed him to the prestigious position of Secretary of State. As a result, critics alleged that the two had agreed to a "corrupt bargain".

Adams was defeated by Democrat Andrew Jackson in the bitter 1828 presidential election. Clay won election to the U.S. Senate in 1831 and ran as the National Republican nominee in the 1832 presidential election. Clay was defeated decisively by President Jackson primarily due to his support for the national bank, which Jackson vehemently opposed. After the 1832 election, Clay helped bring an end to the nullification crisis by leading passage of the Tariff of 1833. During Jackson's second term, opponents of the president including Clay, Webster, and William Henry Harrison created the Whig Party, and through the years, Clay became a leading congressional Whig.

Clay sought the presidency in the 1840 election but was passed over at the Whig National Convention in favor of Harrison. When Harrison died and his vice president John Tyler ascended to office in 1841, Clay clashed with Tyler, who broke with Clay and other congressional Whigs. Clay resigned from the Senate in 1842 and won the 1844 Whig presidential nomination, but he was narrowly defeated in the general election by Democrat James K. Polk, who made the annexation of the Republic of Texas his top issue. Clay strongly criticized the subsequent Mexican–American War and sought the Whig presidential nomination in 1848 but was passed over in favor of General Zachary Taylor who went on to win the election. After returning to the Senate in 1849, Clay played a key role in passing the Compromise of 1850, which postponed a crisis over the status of slavery in the territories. Clay was one of the most important and influential political figures of his era.

Henry Clay was born on April 12, 1777, at the Clay homestead in Hanover County, Virginia. He was the seventh of nine children born to the Reverend John Clay and Elizabeth (née Hudson) Clay. Almost all of Henry's older siblings died before adulthood. His father, a Baptist minister nicknamed "Sir John", died in 1781, leaving Henry and his brothers two enslaved individuals each; he also left his wife 18 slaves and 464 acres (188 ha) of land. Clay was of entirely English descent; his ancestor, John Clay, settled in Virginia in 1613. The Clay family became a well-known political family including three other US senators, numerous state politicians, and Clay's cousin Cassius Clay, a prominent anti-slavery activist active in the mid-19th century.

The British raided Clay's home shortly after the death of his father, leaving the family in a precarious economic position. However, the widow Elizabeth Clay married Captain Henry Watkins, a successful planter and cousin to John Clay. Elizabeth would have seven more children with Watkins, bearing a total of sixteen children. Watkins became a kind and supportive stepfather and Clay had a very good relationship with him. After his mother's remarriage, the young Clay remained in Hanover County, where he learned how to read and write. In 1791, Watkins moved the family to Kentucky, joining his brother in the pursuit of fertile new lands in the West. However, Clay did not follow, as Watkins secured his temporary employment in a Richmond emporium, with the promise that Clay would receive the next available clerkship at the Virginia Court of Chancery.

After Clay had worked at the Richmond emporium for a year, he obtained a clerkship that had become available at the Virginia Court of Chancery. Clay adapted well to his new role, and his handwriting earned him the attention of College of William & Mary professor George Wythe, a signer of the Declaration of Independence, mentor of Thomas Jefferson, and judge on Virginia's High Court of Chancery. Hampered by a crippled hand, Wythe chose Clay as his secretary and amanuensis, a role in which Clay would remain for four years. Clay began to read law under Wythe's mentorship. Wythe had a powerful effect on Clay's worldview, with Clay embracing Wythe's belief that the example of the United States could help spread human freedom around the world. Wythe subsequently arranged a position for Clay with Virginia attorney general Robert Brooke, with the understanding that Brooke would finish Clay's legal studies. After completing his studies under Brooke, Clay was admitted to the Virginia Bar in 1797.

On April 11, 1799, Clay married Lucretia Hart (1781–1864) at the Hart home in Lexington, Kentucky. Her father, Colonel Thomas Hart, was an early settler of Kentucky and a prominent businessman. Hart proved to be an important business connection for Clay, as he helped Clay gain new clients and grow in professional stature. Hart was the namesake and grand-uncle of Missouri Senator Thomas Hart Benton and was also related to James Brown, a prominent Louisiana politician, and Isaac Shelby, the first governor of Kentucky. Henry Clay was an active Freemason, and served as worshipful master of Lexington lodge No.1 in 1801. Henry and Lucretia would remain married until his death in 1852; she lived until 1864, dying at the age of 83. Both are buried at Lexington Cemetery.