A-class submarine may refer to one of these classes of submarine:

• A-class submarine, a class of 13 submarines of the Royal Navy that served in World War I
• Havmanden-class submarine, a class of six built for the Royal Danish Navy, 1911–1914
• Norwegian A-class submarine, a class built for the Royal Norwegian Navy in 1913
• American Holland-class submarine, also later known as Soviet A-class submarine, submarines launched in 1916
• Spanish A-class submarine, a class of three Spanish submarines launched in 1917
• Plunger-class submarine, a class of seven United States Navy submarines built before World War I; also known as the "A class"
• Amphion-class submarine (also called the Archeron class), a class of sixteen submarines of the Royal Navy that served in World War II; also known as the "A class"
• The Japanese Type A submarine, three classes submarines:
  • I-9-class submarine (Type A1 submarine)
  • I-12-class submarine (Type A2 submarine)
  • I-13-class submarine (Type AM submarine)