William Clark (August 1, 1770 – September 1, 1838) is an American explorer, soldier, Indian agent, and territorial governor.

A native of Virginia, he grows up in pre-statehood Kentucky before later settling in what becomes the state of Missouri.

Clark is a planter and slaveholder.

Together with Meriwether Lewis, Clark leads the Lewis and Clark Expedition of 1803 to 1806 across the Louisiana Purchase to the Pacific Ocean, and claims the Pacific Northwest for the United States.

Before the expedition, he serves in a militia and the United States Army.

Afterward, he serves in a militia and as governor of the Missouri Territory.

From 1822 until his death in 1838, he serves as Superintendent of Indian Affairs.