Several classes of destroyer have been known as "M". These include:
Admiralty M-class destroyer, a class of Royal Navy destroyers built 1913–1916 and that served in World War I Hawthorn Leslie M-class destroyer, a variant of the above class Thornycroft M-class destroyer, a variant of the Admiralty design Yarrow M-class destroyer, a variant of the Admiralty design L and M-class destroyer, a class of Royal Navy destroyers launched 1939–1942 and that served in World War II Marcílio Dias-class destroyer, three ships of the Brazilian Navy that served in World War II
See also M class (disambiguation)