* 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 )

* 1521 – Pope Leo X ( b. 1475 )

* 1475 – Pope Leo X ( d. 1521 )

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

* 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.

* 1521 – The Diet of Worms ends when Charles V, Holy Roman Emperor, issues the Edict of Worms, declaring Martin Luther an outlaw.

After undertaking a diplomatic mission to the Holy Roman Emperor, Charles V, accompanying Thomas Wolsey to Calais and Bruges, More was knighted and made under-treasurer of the Exchequer in 1521.

Francis I had already begun war with Charles V in Navarre, and in Italy, too, the French made the first hostile movement on 23 June 1521.

In his anger he appealed to force, and his Epistola ad Carolum V ( 18 February 1521 ) called on the emperor to take measures against Luther, an appeal soon answered by the Edict of Worms ( May 1521 ).

* 1521 and 1523: Envoy to Holy Roman Emperor Charles V.

In 1521, Emperor Charles V added the city to his possessions in the Low Countries, leading to a period of religious strife and economic decline.

In the contest for the imperial throne upon the death of Maximilian in 1519, Sickingen accepted bribes from King Francis I of France, but when the election took place he led his troops to Frankfurt, where their presence assisted to secure the election of Charles V. For this service he was made imperial chamberlain and councillor, and in 1521 he led an expedition into France, which ravaged Picardy, but was beaten back from Mézières and forced to retreat.

It was conducted from 28 January to 25 May 1521, with Emperor Charles V presiding.

Emperor Charles V commenced the Imperial Diet of Worms on 28 January 1521.

He received the imperial investiture from emperor Charles V on April 7, 1521.

Relations between the two countries worsened soon after the event when Cardinal Wolsey arranged an alliance with Charles V, who declared war on France later that year commencing the Italian War of 1521 – 1526.

* Edict of Worms ( 1521 ), by the Diet of Worms, with Holy Roman Emperor Charles V presiding.

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 view that it was composed in connection with the Diet of Speyer ( 1529 ) at which the German Lutheran princes lodged their protest to Emperor Charles V, who wanted to enforce his Edict of Worms ( 1521 ).

At the 1521 Diet of Worms Emperor Charles V had Martin Luther banned and the proliferation of his writings prohibited, which in 1529 provoked the Protestation at Speyer by several Lutheran estates.

De Ayllón had received from Charles V in 1523 a grant for the land explored in 1521 by Francisco Gordillo and slave trader Captain Pedro de Quejo ( de Quexo ).

The peace, however, would last only four years ; the election of Charles V as Holy Roman Emperor in 1519 caused Francis, who had desired the position for himself, to begin the Italian War of 1521 – 26.

He became a close confidant of the young Charles V as well as his Chamberlain ( 1510 ), becoming his Upper Chamberlain upon the death of William of Croÿ-Chièvres in 1521.

Shocked by the defeat of the French in the Italian War of 1521, Pope Clement VII, together with the Republic of Venice, began to organize an alliance to drive Charles V from Italy.

He twice visited Emperor Charles V in 1521 in an effort to convince him against declaring war on Francis I.