* 1667 – Louise of Mecklenburg-Güstrow ( d. 1721 )

Alexander Selkirk ( 1676 – 13 December 1721 ) was a Scottish sailor who spent four years as a castaway after being marooned on an uninhabited island.

* 1721 – Michel Chamillart, French statesman ( b. 1652 )

* 1665 – Jacques Lelong, French bibliographer ( d. 1721 )

* 1721 – Roger Sherman, American statesman and signer of the U. S. Declaration of Independence ( d. 1793 )

* 1721 – Granville Leveson-Gower, 1st Marquess of Stafford, English politician ( d. 1803 )

* 1648 – John Sheffield, 1st Duke of Buckingham and Normanby, English statesman and poet ( d. 1721 )

* Pierre Coustant ( 1654 – 1721 )

* Catherine of Siena ( 1707 – 1721 ) Opere, ed.

* 1721 – Richard Lumley, 1st Earl of Scarbrough, English statesman ( b. 1640 )

* 1721 – James Elphinston, British philologist ( d. 1809 )

* 1721 – Guillaume-Chrétien de Lamoignon de Malesherbes, French statesman ( d. 1794 )

* 1721 – François Hemsterhuis, Dutch philosopher ( d. 1790 )

* 1721 – Peter Pelham, English-born American musician and composer ( d. 1805 )

* 1721 – Alexander Selkirk, Scottish sailor and castaway ( b. 1676 )

Elihu Yale ( April 5, 1649 – July 8, 1721 ) was an American merchant and philanthropist, governor of the East India Company settlement at Madras and a benefactor of the Collegiate School of Connecticut, which in 1718 was named Yale College in his honor.

* 1721 – John McKinly, American physician ( d. 1796 )

* 1721 – Christian Friedrich Heinecken, German child prodigy ( d. 1725 )

* 1721 – John Reid, British army general and composer ( d. 1807 )

Rabbi Yedidiah Tiah Weil ( 1721 – 1805 ), a Prague resident, who described the creation of golems, including those created by Rabbi Avigdor Kara of Prague, did not mention the Maharal, and Rabbi Meir Perels ' biography of the Maharal published in 1718 does not mention a golem.

* 1721 March – Philip V of Spain requested the restitution of Gibraltar to proceed to the renewal of the trade licences of Great Britain with the Spanish possessions in America.

* 1721 1 June – George I sent a letter to Philip V promising " to make use of the first favourable Opportunity to regulate this Article ( the Demand touching the Restitution of Gibraltar ), with the Consent of my Parliament ".

Their purpose was defense from attacks from water and their construction was urged by the Great Northern War of 1700 – 1721.

* 1790 – François Hemsterhuis, Dutch philosopher ( b. 1721 )

* April 4 – Grinling Gibbons, Dutch-born woodcarver ( d. 1721 )

Grinling Gibbons ( 4 April 1648 – 3 August 1721 ) was an English sculptor and wood carver known for his work in England, including St Paul's Cathedral, Blenheim Palace and Hampton Court Palace.

* Grinling Gibbons ( 1648 – 1721 ), a master wood carver

In 1721 he succeeded Grinling Gibbons as " Master Carpenter " and in 1726 he succeeded Vanbrugh as Comptroller of the King's Works, largely to the influence of Walpole.

* 1664 – Matthew Prior, English poet and diplomat ( d. 1721 )

* 1721 – James Craggs the Elder, English politician ( b. 1657 )

* 1721 – Mark Akenside, English poet and physician ( d. 1770 )

* 1636 – Edward Colston, English merchant and philanthropist ( d. 1721 )

The first occurrence in English of " ontology " as recorded by the OED ( Oxford English Dictionary, second edition, 1989 ) appears in Nathaniel Bailey's dictionary of 1721, which defines ontology as ' an Account of being in the Abstract ' - though, of course, such an entry indicates the term was already in use at the time.

* 1721 – Matthew Prior, English poet and diplomat ( b. 1664 )

* April 7 – John Sheffield, 1st Duke of Buckingham and Normanby, English statesman and poet ( d. 1721 )

* October 31 – Prince William Augustus, Duke of Cumberland, English military leader ( b. 1721 )

* June 10 – James Craggs the Elder, English politician ( d. 1721 )

* October 26 – Granville Leveson-Gower, 1st Marquess of Stafford, English politician ( b. 1721 )

* March 26 – John Mudge, English physician and inventor ( b. 1721 )

* June 25 – Thomas Sandby, English cartographer and architect ( b. 1721 )

* December 4 – Wiseman Claget, English classical scholar ( b. 1721 )

* September 4 – John Fielding, English magistrate and social reformer ( b. 1721 )

* February 6 – William Dowdeswell, English politician ( b. 1721 )

* July 21 – Matthew Prior, English poet and diplomat ( d. 1721 )

* April 9 – James Craggs the Younger, English politician ( d. 1721 )

* Thomas Acton ( 1662 – 1721 ), English Jesuit

Early satirical works included an Emblematical Print on the South Sea Scheme ( c. 1721 ), about the disastrous stock market crash of 1720 known as the South Sea Bubble, in which many English people lost a great deal of money.

South Hadley was an uninhabited area of Hadley from 1659 until 1721 when the first English settlers arrived from Hadley.