A flotilla leader was a warship of late 19th century and early 20th century navies suitable for commanding a flotilla of destroyers or other small warships, typically a small cruiser or a large destroyer. The flotilla leader provided space, equipment and staff for the flotilla commodore, including a wireless room, senior engineering and gunnery officers, and administrative staff to support the officers. Originally, older light or scout cruisers were often used, but in the early 1900s, the rapidly increasing speed of new destroyer designs meant that such vessels could no longer keep pace with their charges. Accordingly, large destroyer designs were produced for use as leaders.

Destroyer leader (DL) was the United States Navy designation for large destroyers from 9 February 1951 through the early years of the Cold War. United States ships with hull classification symbol DL were officially frigates from 1 January 1955 until 1975. The smaller destroyer leaders were reclassified as destroyers and the larger as cruisers by the United States Navy 1975 ship reclassification so destroyer escorts could be reclassified as frigates (FF) in conformance with international usage of the term.