* 1521 – Tenochtitlan ( present day Mexico City ) falls to conquistador Hernán Cortés.

* 1521 – Martin Luther's first appearance before the Diet of Worms to be examined by the Holy Roman Emperor Charles V and the other estates of the empire.

Category: People of the Polish – Teutonic War 1519 – 1521 ( German side )

* 1521 – The Ottoman Turks occupy Belgrade.

* 1521 – The Ottoman Turks capture Nándorfehérvár, now known as Belgrade.

* 1521 – Trial of Martin Luther begins its second day during the assembly of the Diet of Worms.

* 1521 – Battle of Villalar: King Charles I of Spain defeats the Comuneros.

* 1521 – Trial of Martin Luther over his teachings begins during the assembly of the Diet of Worms.

* 1521 – Zhengde Emperor of China ( b. 1491 )

* 1521 – Battle of Mactan: Explorer Ferdinand Magellan is killed by natives in the Philippines led by chief Lapu-Lapu.

* 1521 – Ferdinand Magellan, Portuguese explorer ( b. 1480 )

* 1521 – Pope Urban VII ( d. 1590 )

* 1521 – Ferdinand Magellan arrives at Cebu.

A fishing colony was established on the island about 1521 – 22 by the Portuguese under João Álvares Fagundes.

Cuauhtémoc ( also known as Cuauhtemotzin, Guatimozin or Guatemoc ; c. 1495 – 28 February 1525 ) was the Aztec ruler ( tlatoani ) of Tenochtitlan from 1520 to 1521.

* 1521 – Takeda Shingen, Japanese warlord ( d. 1573 )

* 1475 – Pope Leo X ( d. 1521 )

* 1597 – Petrus Canisius, Dutch Jesuit ( b. 1521 )

* 1521 – Pope Sixtus V ( d. 1590 )

* 1521 – Manuel I of Portugal ( b. 1469 )

The only pre-Columbian North American rulers to be commonly called emperors were the Hueyi Tlatoani of the Aztec Empire ( 1375 – 1521 ).

* Sebastian Brant ( 1457 – 1521 )

* 1521 – Pope Leo X excommunicates Martin Luther in the papal bull Decet Romanum Pontificem.

Pope Urban VII ( 4 August 1521 – 27 September 1590 ), born Giovanni Battista Castagna, was Pope for thirteen days in September 1590, the shortest papal reign in history.

Pope Leo X ( 11 December 1475 – 1 December 1521 ), born Giovanni di Lorenzo de ' Medici, was the Pope from 1513 to his death in 1521.

Having fallen ill with malaria, Pope Leo X died on 1 December 1521, so suddenly that the last sacraments could not be administered ; but the contemporary suspicions of poison were unfounded.

* August 27 – Pope Sixtus V ( b. 1521 )

* September 27 – Pope Urban VII ( b. 1521 )

* December 11 – Pope Leo X ( d. 1521 )

The death of Pope Leo in 1521 interrupted Medici power briefly, until Cardinal Giulio de ' Medici was elected Pope Clement VII in 1523.

The Medici produced four Popes of the Catholic Church — Pope Leo X ( 1513 – 1521 ), Pope Clement VII ( 1523 – 1534 ), Pope Pius IV ( 1559 – 1565 ), and Pope Leo XI ( 1605 ); two regent queens of France — Catherine de ' Medici ( 1547 – 1559 ) and Marie de ' Medici ( 1600 – 1610 ); and, in 1531, the family became hereditary Dukes of Florence.

Pope Sixtus V ( 13 December 1521 – 27 August 1590 ), born Felice Peretti di Montalto, was Pope from 1585 to 1590.

Pope Leo X first granted the title " Defender of the Faith " to King Henry VIII in 1521, rewarding him for his support of the Papacy during the early years of the Protestant Reformation, particularly for his book the Defence of the Seven Sacraments.

Pope Leo X ( 1513 – 1521 ) decreed that the use of the name Scotia be confined to referring to land that is now Scotland.

* 1564 – Hans Leo Hassler German composer and organist ( d. 1521 )

Leo treated the Uniate Greeks with great loyalty, and by bull of 18 May 1521 forbade Latin clergy to celebrate mass in Greek churches and Latin bishops to ordain Greek clergy.

Leo followed by formally excommunicating Luther by the bull Decet Romanum Pontificem or It Pleases the Roman Pontiff, on 3 January 1521.

Leo sent a new nuncio to Copenhagen ( 1521 ) in the person of the Minorite Francesco de Potentia, who readily absolved the king and received the rich bishopric of Skara.

The first of these journeys, late in the autumn of 1521, was fruitless on account of the death of Leo X, but his second journey in 1523 was successful.

In 1521, two years after the Fourth Lateran Council had forbidden the establishment of new religious institutes, Pope Leo X appointed a religious rule with simple vows for those tertiaries attached to existing institutes who undertook to live in a community.

From May 1521 until March 1522, Martin Luther stayed at the castle, after he had been taken there for his safety at the request of Frederick the Wise following his excommunication by Pope Leo X and his refusal to recant at the Diet of Worms.

Piacenza was ruled by France until 1521, and briefly, under Leo X, it became part of the Papal States.

" Defender of the Faith " has been one of the subsidiary titles of the English and later British monarchs since it was granted on October 11, 1521, by Pope Leo X to King Henry VIII of England.

Frederick was Pope Leo X's candidate for Holy Roman Emperor in 1519 — the pope had awarded him the Golden Rose of virtue on 3 September 1518 — but he helped secure the election of Charles V. Frederick ensured Luther would be heard before the Diet of Worms in 1521 and subsequently secured an exemption from the Edict of Worms for Saxony.

The Medici channelled all their energy on the Papacy, which Leo X held from 1513 – 1521.

Henry had been declared " Defender of the Faith " ( Fidei Defensor ) in 1521 by Pope Leo X for his pamphlet accusing Martin Luther of heresy.

He and his father became private musicians to Pope Leo X in October 1516 ; Francesco's father kept this position until December 1518, but Francesco stayed until Leo's death in 1521.