|Covid-19|January 22 – The Royalist Oxford Parliament is first assembled by King Charles I of England.
January 26 – First English Civil War – Battle of Nantwich: The Parliamentarians defeat the Royalists, allowing them to end the 6-week Siege of Nantwich in Cheshire, England.
February–August – Explorer Abel Tasman's second expedition for the Dutch East India Company maps the north coast of Australia.
January 30 – Battle of Ochmatów: Polish–Lithuanian Commonwealth forces under hetman Stanisław Koniecpolski secure a substantial victory over the horde of Crimean Tatars under Tugay Bey.
February 5 – The first livestock branding law in the US is passed in Connecticut.
March 24 – In England, Roger Williams is granted an official charter for his Rhode Island Colony, allowing the establishment of a general assembly.
April 25 – A popular Chinese rebellion led by Li Zicheng sacks Beijing, prompting Chongzhen, the last emperor of the Ming dynasty, to commit suicide.
May 6 – Johan Mauritius resigns as Governor of Brazil.
May 25 – Ming general Wu Sangui forms an alliance with the invading Manchus and opens the gates of the Great Wall of China at Shanhaiguan pass, letting the Manchus through towards the capital Beijing.
May 26 – Battle of Montijo: The Kingdom of Portugal is victorious over Habsburg Spain in the first major action between the two nations during the Portuguese Restoration War.
May 27 – Battle of Shanhai Pass: The Manchu Qing dynasty and Wu Sangui gain a decisive victory over Li Zicheng's Shun dynasty.
June 3 – Li Zicheng claims himself as the emperor of China.
June 6 – The invading Qing army, with the help of Ming general Wu Sangui, captures Beijing, China. This marks the beginning of Manchu rule over China proper.
July 2 – English Civil War – Battle of Marston Moor: The Parliamentarians crush the Royalists, ending Charles I's hold on the north of England.
September 1 – English Civil War – Battle of Tippermuir: Montrose defeats Lord Elcho's Covenanters, reviving the Royalist cause in Scotland.
September 2 – English Civil War – Second Battle of Lostwithiel: Charles I and the Royalists gain their last major victory.
September 15 – Pope Innocent X succeeds Pope Urban VIII as the 236th pope.
October 1 – the Jews of Mogilev, Polish–Lithuanian Commonwealth, were attacked during Tashlikh.
October 13 –
November – The Castle of Elvas in Portugal resists a 9-day siege by the Spanish during the Portuguese Restoration War.
November 8 – The Shunzhi Emperor, the third emperor of the Qing dynasty, is enthroned in Beijing after the collapse of the Ming dynasty as the first Qing emperor to rule over China.
Sweden's forces defeat those of the Holy Roman Empire in the Battle of Jüterbog.
Areopagitica by John Milton is published in England.
December 9 – As Christina comes of age, she is made ruling queen of Sweden.
December – Plague breaks out in Edinburgh.
The opera Ormindo is first performed in Venice: music by Francesco Cavalli and libretto by Giovanni Faustini.
Sigismund's Column is erected in Warsaw to commemorate King Sigismund III Vasa, who moved the capital of Poland from Kraków to Warsaw in 1596.
Philosopher René Descartes publishes Principia Philosophiae (Principles of Philosophy).
During the English Civil War, Prince Rupert and his men take Liverpool Castle, which is later reclaimed by Sir John Moore.
Opchanacanough leads the Powhatan Indians in an unsuccessful uprising against the English at Jamestown. This is the last such Indian rebellion of the region.
A Spanish officer is murdered in St. Dominic's Church, Macau during mass by colonists loyal to Portugal during the Portuguese Restoration War.
The West India Company displayed greater interest in profit than in colonization
January 9 – Robert Gibbes, English Landgrave (d. 1715)
Louis François, duc de Boufflers, Marshal of France (d. 1711)
Celestino Sfondrati, Catholic cardinal (d. 1696)
January 11 – Hayashi Hōkō, Japanese philosopher (d. 1732)
January 14 – Thomas Britton, English concert promoter (d. 1714)
January 18 – John Partridge, English astrologer (d. 1708)
January 23 – Jonas Budde (d. 1710)
January 25 – Antoine Thomas, Jesuit priest, missionary, astronomer (d. 1709)
January 26 – Thomas Boylston, American colonist doctor (d. 1695)
Isaac Chayyim Cantarini, Italian rabbi (d. 1723)
Johannes Hancke, German writer (d. 1713)
February 7 – Nils Bielke, member of the High Council of Sweden (d. 1716)
February 8 – Pierre de La Broue, American bishop (d. 1720)
February 12 – Jakob Ammann, Swiss religious leader (d. 1712)
February 24 – Maria Elisabeth Lämmerhirt, mother of Johann Sebastian Bach (d. 1694)
March 1 – Simon Foucher, French polemic (d. 1696)
March 15 – Veit Hans Schnorr von Carolsfeld, German iron and cobalt magnate (d. 1715)
March 21 – Sir Walter Bagot, 3rd Baronet, English politician (d. 1704)
Otto Mencke, German philosopher and scientist (d. 1707)
Sir James Rushout, 1st Baronet, English politician (d. 1698)
March 25 – Heinrich von Cocceji, German jurist from Bremen (d. 1719)
March 31 – Henry Winstanley, English engineer (d. 1703)
April 6 – António Luís de Sousa, 2nd Marquis of Minas, Portuguese general, governor-general of Brazil (d. 1721)
Nathaniel Johnson, American politician (d. 1713)
François de Neufville, duc de Villeroy, French soldier (d. 1730)
April 11 – Marie Jeanne Baptiste of Savoy-Nemours, Duchess of Savoy (d. 1724)
April 17 – Abraham Storck, Dutch painter (d. 1708)
April 21 – Conrad von Reventlow, Danish statesman and the first "Grand Chancellor of Denmark" (d. 1708)
May 2 – Robert Cotton, English politician (d. 1717)
May 4 – Juan Caballero y Ocio, priest remarkable for lavish gifts to the Catholic church and for charity (d. 1707)
May 5 – Sir Richard Newdigate, 2nd Baronet, English landowner (d. 1710)
May 26 – Michael Ettmüller (d. 1683)
June 2 – William Salmon, English medical writer (d. 1713)
June 7 – Johann Christoph Volkamer, German botanist (d. 1720)
June 16 – Henrietta Anne Stuart, Princess of Scotland, England and Ireland (d. 1670)
June 17 – Johann Wolfgang Franck, German baroque composer (d. 1710)
July 2 – Abraham a Sancta Clara (d. 1709)
July 4 – Josceline Percy, 11th Earl of Northumberland, English noble (d. 1670)
July 7 – Joan Geelvinck, Dutch politician (d. 1707)
July 10 – Miguel Bayot, Roman Catholic prelate, Bishop of Cebu (1697–1700) (d. 1700)
July 22 – Peter Drelincourt, Irish chaplain (d. 1722)
Christian Ernst, Margrave of Brandenburg-Bayreuth (1655–1712) (d. 1712)
Louise de La Vallière, French mistress of Louis XIV of France (d. 1710)
August 12 – Heinrich Ignaz Franz Biber, Bohemian composer and violinist (d. 1704)
August 29 – Anne Bourdon, nun in New France (d. 1711)
August 30 – Thomas Tufton, 6th Earl of Thanet, British politician (d. 1729)
September 3 – Richard Newport, 2nd Earl of Bradford, English politician (d. 1723)
September 5 – Gilles Schey, Dutch admiral (d. 1703)
September 6 – Juan Bautista Cabanilles, Spanish composer (d. 1712)
September 11 – Jacob Rotius, Dutch painter (d. 1681)
September 22 – Jacques Échard, French Dominican and historian of the order (d. 1724)
September 25 – Ole Rømer, Danish astronomer (d. 1710)
October 1 – Jean Rousseau, French viol player (d. 1699)
October 2 – François-Timoléon de Choisy, French author (d. 1724)
October 3 – Adriaen Frans Boudewijns, Landscape painter (d. 1719)
October 12 – Christopher Sandius, Arian writer (d. 1680)
October 13 – Sipihr Shikoh, Mughal Empire emperor (d. 1708)
October 24 – William Penn, English Quaker and founder of Pennsylvania (d. 1718)
October 26 – Mathias Steuchius, Swedish archbishop (d. 1730)
November 23 – Cornelia van der Gon, Dutch art collector (d. 1701)
December 8 – Maria d'Este, Italian noble (d. 1684)
December 9 – Robert Kirk, Scottish folklorist, Bible translator, Gaelic scholar (d. 1692)
December 23 – Tomás de Torrejón y Velasco, Spanish composer, musician and organist (d. 1728)
December 25 – Walter Scott, Earl of Tarras, Scottish nobleman (d. 1693)
December 29 – Philips van Almonde, Dutch Lieutenant Admiral (d. 1711)
Antonio Stradivari, Italian violin maker (d. 1737)
Matsuo Bashō, Japanese poet (d. 1694)
March 15 – Countess Louise Juliana of Nassau, Regent of Bohemia (b. 1576)
April 10 – Reverend William Brewster, Pilgrim leader (b. 1567)
April 25 – Chongzhen, last Ming Emperor of China (suicide) (b. 1611)
July 29 – Pope Urban VIII (b. 1568)
September 7 – Guido Bentivoglio, Italian statesman and historian (b. 1579)
John Coke, English politician (b. 1563)
Francis Quarles, English poet (b. 1592)
October 6 – Elisabeth of France, queen of Philip IV of Spain (b. 1602)
November 6 – Thomas Roe, English diplomat (b. c. 1581)
November 10 – Luis Vélez de Guevara, Spanish writer (b. 1579)
December 28 – John Bankes, Attorney General and Chief Justice to King Charles I of England (b. 1589)
December 30 – Jan Baptist van Helmont, Flemish chemist (b. 1577)
1644 (MDCXLIV) was a leap year starting on Friday (dominical letter CB) of the Gregorian calendar and a leap year starting on Monday (dominical letter GF) of the Julian calendar, the 1644th year of the Common Era (CE) and Anno Domini (AD) designations, the 644th year of the 2nd millennium, the 44th year of the 17th century, and the 5th year of the 1640s decade. As of the start of 1644, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.