USS John S. McCain (DDG-56) is an Arleigh Burke-class destroyer in the United States Navy. She is part of the 7th Fleet and homeported at Yokosuka Naval Base in Yokosuka, Japan.

The ship is named after John S. McCain, Jr. and John S. McCain, Sr., both Admirals in the United States Navy. John S. McCain Jr. commanded the submarines USS Gunnel and Dentuda during World War II. Subsequently he held a number of posts, rising to Commander-in-Chief of the United States Pacific Command before retiring in 1972. John S. McCain Sr. commanded the aircraft carrier Ranger (CV-4), and acted as commander of the Fast Carrier Task Force during the latter stages of World War II. They were respectively the father and grandfather of John S. McCain III, former naval aviator captain, U.S. Senator representing Arizona, and Republican nominee for president in the 2008 election.

John S. McCain's keel was laid down on September 3, 1991 at the Bath Iron Works (BIW) in Bath, Maine. The ship was launched on September 26, 1992, sponsored by Cindy McCain, wife of Senator McCain. John S. McCain was commissioned on July 2, 1994 at Bath Iron Works; former President George H. W. Bush, was the ceremony's principal speaker.