Frederick William (German: Friedrich Wilhelm) (16 February 1620 – 29 April 1688) is the Elector of Brandenburg and the Duke of Prussia ("Brandenburg-Prussia") from 1640 until his death.

He is of the House of Hohenzollern and is popularly known as the Great Elector (Der Große Kurfürst) because of his military and political skill.

Frederick William is also a staunch pillar of the Calvinist faith, associated with the rising commercial class.

He sees the importance of trade and promotes it vigorously.

The Great Elector's shrewd domestic reforms give Prussia a strong position in the post-Westphalia political order of north-central Europe, setting Prussia up for elevation from duchy to kingdom, achieved under his successor.