|Covid-19|April – Martin Luther helps Katharina von Bora, his eventual wife, escape from the Nimbschen convent by placing her and 12 other nuns in herring barrels.
May – The Ningbo Incident: Two rival trade delegations from Japan feud in the Chinese city of Ningbo, resulting in the pillage and plunder of the city.
June 6 – Gustav Vasa is elected king of Sweden, finally establishing its full independence of Sweden from Denmark, marking the end of the Kalmar Union.
July 1 – Johann Esch and Heinrich Voes became the first Flemish Lutheran martyrs, burned at the stake by Roman Catholic authorities in Brussels.
November 19 – Pope Clement VII succeeds Pope Adrian VI as the 219th pope.
The Ming Dynasty Chinese navy captures two Western ships with Portuguese breech–loading culverins aboard, which the Chinese call a fo–lang–ji (Frankish culverin). According to the Ming Shi, these cannons are soon presented to the Jiajing Emperor by Wang Hong, and their design is copied in 1529.
Martin Luther's translation of the Pentateuch into German (Das allte Testament Deutsch) is published.
Wijerd Jelckama, a Frisian warlord and military commander is executed in Leeuwarden. His death ends the successful Frisian rebellion fought by the Arumer Black Heap.
The Swabian League destroyed 23 robber baron castles in the Franconian War.
January 29 – Enea Vico, Italian engraver (d. 1567)
February 1 – Francesco Abbondio Castiglioni, Roman Catholic cardinal (d. 1568)
February 13 – Valentin Naboth, German astronomer and mathematician (d. 1593)
February 20 – Jan Blahoslav, Czech writer (d. 1571)
March 17 – Giovanni Francesco Commendone, Catholic cardinal (d. 1584)
March 21 – Kaspar Eberhard, German theologian (d. 1575)
April 5 – Blaise de Vigenère, French diplomat and cryptographer (d. 1596)
April 21 – Marco Antonio Bragadin (d. 1571)
June 5 – Margaret of France, Duchess of Berry (d. 1574)
July 4 – Pier Francesco Orsini, Italian condottiero and art patron (d. 1583)
July 18 – George II of Brieg, Duke of Brieg (1547–1586) (d. 1586)
September 21 – Sancho d'Avila, Spanish General (d. 1583)
September 22 – Charles, Cardinal de Bourbon, French church leader and pretender to the throne (d. 1590)
October 10 – Ludwig Rabus, German martyrologist (d. 1592)
October 11 – Eleonore of Fürstenberg, Wife of Philip IV, Count of Hanau-Lichtenberg (d. 1544)
October 18 – Anna Jagiellon, daughter of Sigismund I of Poland (d. 1596)
Sancho d'Avila, Spanish military leader (d. 1583)
Gabriele Falloppio, Italian anatomist and physician (d. 1562)
Martín Cortés, Spanish conquistador (d. 1589)
Henry Brandon, Earl of Lincoln, nephew of King Henry VIII, son of Charles Brandon, Duke of Suffolk
Francisco Foreiro, Portuguese Dominican theologian and biblist (d. 1581)
Gaspara Stampa, Italian poet (d. 1554)
probable – Crispin van den Broeck, Flemish painter (d. 1591)
possible – Catherine Howard, Fifth Queen of Henry VIII of England, (born in between 1518 and 1524; d. 1542)
February 4 – Thomas Ruthall, Chancellor of the University of Cambridge
May 7 – Franz von Sickingen, German knight (b. 1481)
May 23 – Ashikaga Yoshitane, Japanese shogun (b. 1466)
May 24 – Henry Marney, 1st Baron Marney, English politician (b. 1447)
July 1 – Johann Esch and Heinrich Voes, Flemish Lutheran martyrs
August 13 – Gerard David, Flemish artist (b. c. 1455)
August 29 – Ulrich von Hutten, Lutheran reformer (b. 1488)
September 14 – Pope Adrian VI (b. 1459)
October – William Cornysh, English composer (b. 1465)
December 12 – Pietro Perugino, Italian painter (b. 1446)
Wijerd Jelckama, Frisian rebel and warlord (b. 1490)
Alessandro Alessandri, Italian jurist (b. 1461)
Bartolomeo Montagna, Italian painter (b. 1450)
Abi Ahmet Celebi, chief physician of the Ottoman Empire, (b. 1436)
Year 1523 (MDXXIII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar.