John Marshall (September 24, 1755 – July 6, 1835) was an American jurist and statesman whose court opinions helped lay the basis for American constitutional law while enhancing the role of the Supreme Court as a center of power. Marshall was the fourth Chief Justice of the United States, serving from 1801 until his death in 1835. He had served in the United States House of Representatives from 1799 to 1800, and was Secretary of State under President John Adams from 1800 to 1801. Marshall was from the Commonwealth of Virginia and was a leader of the Federalist Party.

The longest-serving Chief Justice of the United States, Marshall dominated the Court for over three decades (a term outliving his own Federalist Party) and played a significant role in the development of the American legal system. Most notably, he reinforced the principle that federal courts are obligated to exercise judicial review, by disregarding purported laws if they violate the Constitution. Thus, Marshall cemented the position of the American judiciary as an independent and influential branch of government. Furthermore, the Marshall Court made several important decisions relating to federalism, affecting the balance of power between the federal government and the states during the early years of the republic. In particular, he repeatedly confirmed the supremacy of federal law over state law, and supported an expansive reading of the enumerated powers.

John Marshall was born in a log cabin close to Germantown, a rural community on the Virginia frontier, in what is now Fauquier County near Midland, Virginia, on September 24, 1755, to Thomas Marshall and Mary Randolph Keith, the daughter of Thomas Randolph of Tuckahoe. The oldest of fifteen, John had eight sisters and six brothers. Also, several cousins were raised with the family. He was also relative of Thomas Jefferson, both of them being descendants of Virginia colonist William Randolph, though Marshall and Jefferson would oppose each other on many political issues. From a young age, he was noted for his good humor and black eyes, which were "strong and penetrating, beaming with intelligence and good nature".