Tecumseh (/tɪˈkʌmsə, tɪˈkʌmsi/ ti-KUM-sə, ti-KUM-see; March 1768 – October 5, 1813) was a Native American Shawnee warrior and chief, who became the primary leader of a large, multi-tribal confederacy in the early 19th century. Born in the Ohio Country (present-day Ohio), and growing up during the American Revolutionary War and the Northwest Indian War, Tecumseh was exposed to warfare and envisioned the establishment of an independent Native American nation east of the Mississippi River under British protection. He worked to recruit additional members to his tribal confederacy from the southern United States.

Tecumseh was among the most celebrated Native American leaders in history and was known as a strong and eloquent orator who promoted tribal unity. He was also ambitious, willing to take risks, and make significant sacrifices to repel the settlers from Native American lands in the Old Northwest Territory. In 1808, with his brother Tenskwatawa ("The Prophet"), Tecumseh founded the Native American village the European Americans called Prophetstown, north of present-day Lafayette, Indiana. Prophetstown grew into a large, multi-tribal community and a central point in Tecumseh's political and military alliance.

Tecumseh's confederation fought the United States during Tecumseh's War, but he was unsuccessful in getting the U.S. government to rescind the Treaty of Fort Wayne (1809) and other land-cession treaties. In 1811, as he traveled south to recruit more allies, his brother Tenskwatawa defended Prophetstown against William Henry Harrison's army at the Battle of Tippecanoe, but the Native Americans retreated from the field and the European Americans unearthed graves and burned Prophetstown. Although Tecumseh remained the military leader of the pan-Native American confederation, his plan to enlarge the Native American alliance was never fulfilled.

Tecumseh and his confederacy continued to fight the United States after forming an alliance with Great Britain in the War of 1812. During the war, Tecumseh's confederacy helped in the capture of Fort Detroit. However, after U.S. naval forces took control of Lake Erie in 1813, the British and their Native American allies retreated into Upper Canada, where the European American forces engaged them at the Battle of the Thames on October 5, 1813, and Tecumseh was killed. His death and the end of the war caused the pan-Native American alliance to collapse. Within a few years, the remaining tribal lands in the Old Northwest were ceded to the U.S. government and subsequently opened for new settlement and most of the Native Americans eventually moved west, across the Mississippi River. Since his death Tecumseh has become an iconic folk hero in American, Indigenous, and Canadian history.