William Clark (August 1, 1770 – September 1, 1838) was an American explorer, soldier, Indian agent, and territorial governor. A native of Virginia, he grew up in prestatehood Kentucky before later settling in what became the state of Missouri. Clark was a planter and slaveholder.
Along with Meriwether Lewis, Clark helped lead the Lewis and Clark Expedition of 1803 to 1806 across the Louisiana Purchase to the Pacific Ocean, and claimed the Pacific Northwest for the United States. Before the expedition, he served in a militia and the United States Army. Afterward, he served in a militia and as governor of the Missouri Territory. From 1822 until his death in 1838, he served as Superintendent of Indian Affairs.