|Covid-19|January 23 – Thirty Years' War: Sweden and France sign the Treaty of Bärwalde, a military alliance in which France provides funds for the Swedish army invading northern Germany.
February 5 – Roger Williams emigrates to Boston.
February 16 – The Reval Gymnasium is founded in Tallinn, Estonia by Swedish king Gustavus II Adolphus.
April 13 – Thirty Years' War: Gustavus Adolphus of Sweden defeats an imperial garrison at the city of Frankfurt an der Oder.
May 10 – Thirty Years' War: After a two-month siege, an Imperial army under the command of Tilly storms the German city of Magdeburg and brutally sacks it, massacring over 20,000 inhabitants. Shocked by the massacre, many protestant states in the Holy Roman Empire decide to ally with Gustavus Adolphus of Sweden and support his ongoing invasion.
May 18 – In Dorchester, Massachusetts, John Winthrop takes the oath of office and becomes the first Governor of Massachusetts.
La Gazette, the first French newspaper, was founded.
Thirty Years' War: Bavaria and France sign the Treaty of Fontainebleau, forming a secret alliance. The secret alliance does not last long, however.
June 19 – War of the Mantuan Succession: The Treaty of Cherasco is signed, ending the War of Mantuan Succession.
June 20 – Algerian pirates sack Baltimore, County Cork in Ireland.
July 16 – The city of Würzburg is taken by Gustavus Adolphus of Sweden, putting an end to the Würzburg witch trials, but not before an estimated 900 people from the city and its environs had been burned at the stake for witchcraft.
July 22 – Thirty Years' War: Tilly defeats Gustavus Adolphus of Sweden at the Battle of Werben, but not decisively.
End of August – Thirty Years' War: Running out of supply, Tilly is forced to send his army into the Electorate of Saxony in order to secure supplies, as well as to force a reaction from John George, Elector of Saxony and Gustavus Adolphus of Sweden.
September 11 – Thirty Years' War: As a result of Tilly's invasion, John George, Elector of Saxony, who had until now stayed neutral, allies with Gustavus Adolphus of Sweden in order to drive the Imperial army out of Saxony.
September 12 – Eighty Years' War: A Spanish fleet under the command of admiral Antonio de Oquendo defeats a Dutch fleet off the coast of Brazil in the Battle of Albrolhos.
September 12 and 13 – Eighty Years' War: A Spanish fleet carrying an invasion force is intercepted and almost completely destroyed by a Dutch fleet in the Battle of the Slaak.
September 17 – Thirty Years' War: In the Battle of Breitenfeld, Tilly's imperial army is decisively defeated by Gustavus II Adolphus of Sweden, shattering the imperial army of the Holy Roman Empire and marking the first significant victory for the Protestants in the war.
October 10 – Thirty Years' War: A Saxon army takes over Prague.
December 23 – Thirty Years' War: Gustavus II Adolphus of Sweden takes the city of Mainz without any resistance.
Moses Amyraut's Traite des Religions is published.
The Taj Mahal's construction is started (it is finished in 1653).
Mount Vesuvius erupts in Pompeii.
First English settlement by William Claiborne within the State of Maryland, U.S.A.
Chocolate: or, An Indian Drinke, published by Antonio Colmenero de Ledesma
January 1 – Katherine Philips, Anglo-Welsh poet (d. 1664)
January 2 – Anthonie van Borssom, Dutch painter (d. 1677)
January 6 – Anne Hamilton, 3rd Duchess of Hamilton, Scottish peeress (d. 1716)
January 12 – Hasanuddin of Gowa, 16th Ruler of The Sultanate of Gowa (d. 1670)
January 23 – Vincent Houdry, French Jesuit preacher and writer on ascetics (d. 1729)
February 6 – Edward Abney, English politician (d. 1728)
February 10 – Louise of Anhalt-Dessau, Duchess suo jure of Oława and Wołów (1672–1680) (d. 1680)
February 20 – Thomas Osborne, 1st Duke of Leeds, English statesman (d. 1712)
February 22 – Peder Syv, Danish historian (d. 1702)
March 3 – Esaias Boursse, Dutch painter (d. 1672)
March 9 – Claude-François Ménestrier, French heraldist, Jesuit, courtier (d. 1705)
March 13 – Lodewijck Huygens, Dutch diplomat (d. 1699)
March 16 – René Le Bossu, French critic (d. 1680)
April 8 – Cornelis de Heem, painter (d. 1695)
Piero de Bonzi, Catholic cardinal (d. 1703)
Walter Vincent, English politician (d. 1680)
April 21 – Francesco Maidalchini, Catholic cardinal (d. 1700)
April 29 – Joseph Bridger, Colonial Governor of Virginia (d. 1686)
May 2 – John Murray, 1st Marquess of Atholl (d. 1703)
May 4 – William Brereton, 3rd Baron Brereton, English politician (d. 1680)
May 10 – Flavio Chigi, Catholic cardinal (d. 1693)
May 18 – Stanislaus Papczyński, Polish priest (d. 1701)
May 19 – Christoffel Pierson, Dutch painter (d. 1714)
May 28 – Louis André, Jesuit priest, missionary and translator (d. 1715)
May 29 – Robert Paston, 1st Earl of Yarmouth, English politician and Earl (d. 1683)
June 13 – Gilbert Hay, 11th Earl of Erroll, Scottish noble (d. 1674)
June 17 – Gauharara Begum, Mughal noblewoman (d. 1706)
June 22 – Francis Rombouts, Mayor of New York City (d. 1691)
June 25 – António das Chagas, Portuguese Franciscan friar and ascetical writer (d. 1682)
June 26 – Vincenzo Albrici, Italian composer (d. 1695)
July 4 – John Roettiers, English engraver (d. 1703)
Richard Cumberland, English philosopher (d. 1718)
Jens Juel, Danish diplomat (d. 1700)
August 5 – Adam Adamandy Kochański, Polish mathematician (d. 1700)
August 7 – Nicholas Tufton, 3rd Earl of Thanet, English Earl (d. 1679)
Maffeo Barberini, Prince of Palestrina (d. 1685)
John Dryden, English writer (d. 1700)
August 24 – Philip Henry, English minister (d. 1696)
August 29 – Henry Noris, Catholic cardinal (d. 1704)
September 1 – Anne Crawford-Lindsay, Scottish nobility (d. 1689)
September 3 – William Stoughton, American judge at the Salem witch trials (d. 1701)
September 6 – Charles Porter, English-born judge (d. 1696)
Richard Edlin, English astrologer (d. 1677)
Johann Heinrich Roos, Dutch painter (d. 1685)
Toussaint de Forbin-Janson, French Catholic Cardinal and Bishop of Beauvais (d. 1713)
Eugene Maximilian, Prince of Hornes (d. 1709)
October 3 – Sebastian Anton Scherer, German organist and composer (d. 1712)
October 6 – Emmanuel, Prince of Anhalt-Köthen, German prince of the House of Ascania (d. 1670)
October 12 – George Saunderson, 5th Viscount Castleton, Member of the Parliament of England (d. 1714)
October 13 – Richard Hampden, English politician (d. 1695)
Heinrich Müller, German theologian and writer (d. 1675)
Michael Wigglesworth, American puritan minister (d. 1705)
October 22 – Gilles Boileau (d. 1669)
October 26 – Leopold Karl von Kollonitsch, cardinal of the Holy Roman Church (d. 1707)
October 30 – Pierre Beauchamp, French choreographer, dancer and composer (d. 1705)
November 4 – Mary, Princess Royal and Princess of Orange (d. 1660)
November 10 – Daniel Harvey, English merchant and politician (d. 1672)
November 17 – Marco d'Aviano (d. 1699)
November 21 – Catharina Questiers, Dutch poet (d. 1669)
November 28 – Abraham Brueghel, Flemish Baroque painter (d. 1690)
December 14 – Anne Conway, English philosopher (d. 1679)
Bernhard Gustav of Baden-Durlach, Swedish general, and Prince-Abbot of Fulda and Kempten, and cardinal (d. 1677)
Gabrielle Suchon, French moral philosopher and Catholic feminist (d. 1703)
January 1 – Thomas Hobson, English carrier and origin of the phrase "Hobson's choice" (b. 1544)
January 3 – Michelagnolo Galilei, Italian composer and lutenist, younger brother of Galileo Galilei (b. 1575)
March 24 – Philipp Dulichius, German composer (b. 1562)
March 31 – John Donne, English writer and prelate (b. 1572)
May 6 – Sir Robert Cotton, 1st Baronet, of Connington, English politician (b. 1570)
June 17 – Mumtaz Mahal, favorite wife of Shah Jahan (b. 1593)
June 21 – John Smith of Jamestown, English soldier and colonist (b. 1580)
July 19 – Cesare Cremonini, Italian philosopher (b. 1550)
July 28 – Guillén de Castro y Bellvis, Spanish dramatist (b. 1569)
August 8 – Konstantinas Sirvydas, Lithuanian religious leader (b. 1579)
September 6 – Honda Tadamasa, Japanese daimyo (b. 1575)
September 18 – Countess Palatine Dorothea of Simmern (b. 1581)
October 14 – Sophie of Mecklenburg-Güstrow, Queen and regent of Denmark (b. 1557)
26 October – Catherine de Parthenay, French noblewoman and mathematician (b. 1554)
November 1 – Archduchess Maria Maddalena of Austria (b. 1589)
December 23 – Michael Drayton, English poet (b. 1563)
1631 (MDCXXXI) was a common year starting on Wednesday (dominical letter E) of the Gregorian calendar and a common year starting on Saturday (dominical letter B) of the Julian calendar, the 1631st year of the Common Era (CE) and Anno Domini (AD) designations, the 631st year of the 2nd millennium, the 31st year of the 17th century, and the 2nd year of the 1630s decade. As of the start of 1631, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.