|Centuries:||15th century · 16th century · 17th century|
|Decades:||1490s · 1500s · 1510s · 1520s · 1530s · 1540s · 1550s|
|Years:||1518 · 1519 · 1520 · 1521 · 1522 · 1523 · 1524|
|1521 by topic|
|Arts and science|
|Lists of leaders|
|Birth and death categories|
|Establishments and disestablishments categories|
|Ab urbe condita||2274|
|English Regnal year||12 Hen. 8 – 13 Hen. 8|
|Chinese calendar||庚辰年 (Metal Dragon)|
4217 or 4157
— to —
辛巳年 (Metal Snake)
4218 or 4158
|- Vikram Samvat||1577–1578|
|- Shaka Samvat||1442–1443|
|- Kali Yuga||4621–4622|
|Japanese calendar||Eishō 18 / Daiei 1|
|Minguo calendar||391 before ROC|
|Thai solar calendar||2063–2064|
|Wikimedia Commons has media related to 1521.|
- 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.
- March 6
- March 16 – Ferdinand Magellan reaches the Philippines. Starting this year, the Philippines is now one day behind to it's Asian neighbors.
- April 7
- April 16–18 – Martin Luther is examined before Emperor Charles V and the Diet of Worms.
- 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.
- April 27 – Ferdinand Magellan is killed in the Philippines, in the Battle of Mactan.
- May – Italian War of 1521–26 breaks out between Charles V, Holy Roman Emperor, and Francis I of France.
- May 17 – Edward Stafford, 3rd Duke of Buckingham, is executed for treason in London.
- May 20 – Battle of Pampeluna: The French defeat the Spanish.
- May 25 – The Diet of Worms ends when Charles V, Holy Roman Emperor issues the Edict of Worms, declaring Martin Luther an outlaw.
- May 27 – Jiajing Emperor ascends the throne of the Ming dynasty.
- June 29 or 30 – The oldest surviving dateable document written primarily in the Romanian language: Neacșu's letter, written by a trader from Câmpulung, to Johannes Benkner, the mayor of Brașov, warning that the Ottoman Empire is preparing its troops to cross into Wallachia and Transylvania; the script used is Romanian Cyrillic.
- 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: Student rebellion 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.
- August 23 – Christian II of Denmark is deposed as king of Sweden and Gustav Vasa is elected new Swedish regent.
- 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.
- Jacopo Berengario da Carpi publishes Commentaria cum amplissimus additionibus super anatomiam Mundini in Bologna, including observation of the vermiform appendix.
- San Juan Bautista is founded in the archipelago of Puerto Rico.
- The principality of Ryazan is annexed by the Grand Duchy of Moscow.
- March 21 – Maurice, Elector of Saxony (d. 1553)
- April 5 – Francesco Laparelli, Italian architect (d. 1570)
- April 14 – Johann Marbach, German theologian (d. 1581)
- April 18 – François de Coligny d'Andelot, French general (d. 1569)
- May 8 – Petrus Canisius, Dutch Jesuit (d. 1597)
- May 10 – John Ernest, Duke of Saxe-Coburg, (d. 1553)
- June 18 – Maria of Portugal, Duchess of Viseu, daughter of King Manuel I (d. 1577)
- June 21 – John II, Duke of Schleswig-Holstein-Haderslev (d. 1580)
- August 4 – Pope Urban VII (d. 1590)
- August 19 – Lodovico Guicciardini, Italian historian (d. 1589)
- October 1 – Frederick Magnus I, Count of Solms-Laubach, (d. 1561)
- October 9 – Ottavio Farnese, Duke of Parma (d. 1586)
- November 22 – Edmund Sheffield, 1st Baron Sheffield, English Baron (d. 1549)
- November 29 – Marcantonio Maffei, Archbishop and Cardinal (d. 1583)
- December 1 – Takeda Shingen, Japanese warlord (d. 1573)
- December 13 – Pope Sixtus V (d. 1590)
- date unknown
- April 20 – Zhengde Emperor of China (b. 1491)
- April 25 – Juan López de Padilla, Juan Bravo and Francisco Maldonado, executed Spanish rebels
- April 27 – Ferdinand Magellan, Portuguese explorer (b. 1480)
- May 10 – Sebastian Brant, German humanist and satirist (b. 1457)
- May 17 – Edward Stafford, 3rd Duke of Buckingham (executed) (b. 1478)
- June 15 – Tamás Bakócz, Hungarian Catholic cardinal and statesman (b. 1442)
- June 21 – Leonardo Loredan, Doge of Venice (b. 1436)
- July 24 – Juan Ponce de León, Spanish conquistador (b. 1460)
- August 27 – Josquin des Prez, Flemish composer (b. c. 1450)
- October 22 – Edward Poynings, Lord Deputy to King Henry VII of England (b. 1459)
- December 1 – Pope Leo X (b. 1475)
- December 13 – King Manuel I of Portugal (b. 1469)
March–April: Ferdinand Magellan's voyage around the world.
Lorenzo Lotto, Christ Taking Leave of his Mother