From The Art and Popular Culture Encyclopedia
1521 (MDXXI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar, the 1521st year of the Common Era (CE) and Anno Domini (AD) designations, the 521st year of the 2nd millennium, the 21st year of the 16th century, and the 2nd year of the 1520s decade.
- January 3 – Pope Leo X excommunicates Martin Luther, in the papal bull Decet Romanum Pontificem.
- January 22 – Charles V, Holy Roman Emperor, opens the Diet of Worms in Worms, Germany.
- January 27 – Suleiman the Magnificent suppresses a revolt by the ruler of Damascus.
- January 28 – The Diet of Worms begins, lasting until May 25.
- February 2 – The Nydala Abbey Bloodbath take place in Nydala Abbey, Sweden.
- March 6
- March 16 – Ferdinand Magellan reaches the Philippines.
- April 7
- April 16–18 – Martin Luther is examined before Emperor Charles V and the Diet of Worms, where he proclaims, "Here I stand", regarding his belief in the Bible alone, as the standard of Christian doctrine.
- April 24 – Revolt of the Comuneros – Battle of Villalar: Castilian royalists defeat the rebels and execute their three leaders.
- April 26 – Martin Luther leaves Worms and disappears for a year – he is rumored to be murdered, but is actually in hiding at the Wartburg castle.
- May 25 – The Diet of Worms ends when Charles V, Holy Roman Emperor issues the Edict of Worms, declaring Martin Luther an outlaw.
- June 25 – Suleiman the Magnificent begins the siege of Belgrade.
- June 30 – Battle of Esquiroz: French forces under Henri d'Albret, exiled King of Navarre, are defeated by the Spanish, and forced to abandon their attempt to recover Henri's kingdom.
- July – Pfaffensturm: Students rebel against priests in Erfurt.
- August 8 – Fall of Tenochtitlan: Hernán Cortés and allied local indigenous peoples of the Americas defeat the Aztec forces of Cuauhtémoc, the last Tlatoani (Aztec Emperor), at Tenochtitlan in the Valley of Mexico.
- August 13 – Fall of Tenochtitlan: Cuauhtémoc surrenders to Cortés, thus incorporating the Aztec Empire into the Spanish Empire and ending the Late Postclassic period in Mesoamerica.
- August 29 – Belgrade is captured by the Ottoman army of Suleiman the Magnificent.
- November 23 – Spanish–German–Papal forces under Prospero Colonna force French Marshal Odet de Lautrec to abandon Milan.
- December 27 – The Zwickau prophets arrive in Wittenberg, disturbing the peace and preaching the Apocalypse.
- October 1 – Frederick Magnus I, Count of Solms-Laubach, (d. 1561)
- December 13 – Pope Sixtus V (d. 1590)
- Petrus Forestus
- April 27 – Ferdinand Magellan, Portuguese explorer (b. 1480)
- May 10 – Sebastian Brant, German humanist and satirist (b. 1457)
- July – Juan Ponce de León, Spanish conquistador (b. 1460)
- December 1 – Pope Leo X (b. 1475)