William the Younger may refer to:
William Peverel the Younger (c. 1080–1155), son of William Peverel William of Jülich (died 1304), known as the Younger William IV, Duke of Brunswick-Lüneburg (c. 1425–1503), called William the Younger William the Younger, Duke of Brunswick-Lüneburg (1535–1592) William Alexander (the younger) (c. 1602–1638), founder of the Scottish colony at Port-Royal William Cawley (younger) (born c. 1628), English lawyer and politician William Faithorne the Younger (1656–1701?), English mezzotint engraver William Morgan (of Tredegar, younger) (1725–1763), Welsh politician William Pitt the Younger (1759–1806), British statesman William Heberden the Younger (1767–1845), British physician William Godwin the Younger (1803–1832), English reporter and author William Holl the Younger (1807–1871), English portrait and figure engraver William Urwick the younger (1826–1905), Anglo-Irish nonconformist minister and antiquarian chronicler