Fort Ross (Russian: Форт-Росс, or originally, Крепость Россъ, Krepostʹ Ross — Fortress Ross) is a former Russian establishment on the west coast of North America in what is now Sonoma County, California, in the United States. It was the hub of the southernmost Russian settlements in North America in between 1812 to 1842. It has been the subject of archaeological investigation and is a National Historic Landmark and on the National Register of Historic Places. It is part of California's Fort Ross State Historic Park.

Fort Ross is a landmark in the history of European imperialism. The Spanish expansion went west across the Atlantic Ocean and the Russian expansion went east across Siberia and the Pacific Ocean. In the early nineteenth century, the two waves of expansion met on the opposite side of the world along the Pacific Coast of California, with Russia arriving from the north and Spain from the south. The United States of America arrived in 1846 from the east.