1338

1338 (MCCCXXXVIII) was a common year starting on Thursday of the Julian calendar, the 1338th year of the Common Era (CE) and Anno Domini (AD) designations, the 338th year of the 2nd millennium, the 38th year of the 14th century, and the 9th year of the 1330s decade. As of the start of 1338, the Gregorian calendar was 8 days ahead of the Julian calendar, which was the dominant calendar of the time.

• Hundred Years' War: Louis IV, Holy Roman Emperor appoints Edward III of England as a vicar-general of the Holy Roman Empire. Louis supports Edward's claim to the French throne under the terms of the Treaty of Koblenz.
• Philip VI of France besieges Guienne in Southwest France and his navy attacks Portsmouth in England.
• Ashikaga Takauji granted title of Shogun by the emperor of Japan.
• Nicomedia is captured by the Ottoman Empire.

• 21 January – Charles V of France (died 1380)
• 3 February – Joanna of Bourbon (died 1378)
• 5 October – Alexios III of Trebizond (died 1390)
• 29 November – Lionel of Antwerp, 1st Duke of Clarence (died 1368)

• George de Dunbar, 10th Earl of March (died 1420)
• Niccolò II d'Este (died 1388)
• Thomas de Ros, 5th Baron de Ros (died 1383)
• Margaret de Stafford (died 1396)
• Tvrtko I of Bosnia (died 1391)

• 24 April – Theodore I of Montferrat (born c. 1270)
• 5 May – Prince Tsunenaga, son of Japanese Emperor (born 1324)
• July – Muhammad Khan, Persian monarch
• 4 August – Thomas of Brotherton, 1st Earl of Norfolk (born 1300)
• 22 August – William II of Athens (born 1312)

• Kitabatake Akiie, Japanese governor (born 1318)
• Alfonso Fadrique, Sicilian noble
• Awhadi of Maragheh, Persian poet
• Prince Narinaga, Japanese Shogun (born 1325)
• Marino Sanuto the Elder, Venetian statesman and geographer (born c. 1260)
• John Wishart, Scottish bishop
• Nitta Yoshiaki, Japanese Samurai
• Nitta Yoshisada, Japanese Samurai