A class submarine

Five classes of submarine are known as the A class

* "Plunger" class of seven submarines of the United States Navy built before World War I is also known as the "A class".
* British A class submarine (1903) of thirteen submarines of the Royal Navy that served in World War I.
* "Amphion" or "Acheron" class of sixteen submarines of the Royal Navy that served in World War II is also known as the "A class".
* Norwegian A class submarines built for the Royal Norwegian Navy in 1913.
* The Spanish A class of three submarines launched in 1917.
* The Soviet A class submarines, launched in 1916.