USS Green Bay (LPD-20) is a San Antonio-class amphibious transport dock. She is the second ship of the United States Navy to be named for the city and bay of Green Bay, Wisconsin.

The San Antonio class is a class of amphibious transport docks, also called a "landing platform, dock" (LPD), used by the United States Navy. These warships replace the Austin-class LPDs, as well as the Newport-class tank landing ships, the Anchorage-class dock landing ships, and the Charleston-class amphibious cargo ships that have already been retired.