The Parker-class leaders or improved Marksman-class leaders were a class of six destroyer leaders built for the Royal Navy during 1916–17 for World War I service. They were named after famed historical naval leaders, except for Anzac, which was named to honour the Australian and New Zealand Army Corps, and was later transferred to the Royal Australian Navy. They were the last major Royal Navy warships to be ordered with three propeller shafts, a design that was never widely adopted in British warships.

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.