|Ab urbe condita||2373|
|Balinese saka calendar||1541–1542|
|English Regnal year||17 Ja. 1 – 18 Ja. 1|
|Chinese calendar||己未年 (Earth Goat)|
4316 or 4256
— to —
庚申年 (Metal Monkey)
4317 or 4257
|- Vikram Samvat||1676–1677|
|- Shaka Samvat||1541–1542|
|- Kali Yuga||4720–4721|
|Japanese calendar||Genna 6|
|Julian calendar||Gregorian minus 10 days|
|Minguo calendar||292 before ROC|
|Thai solar calendar||2162–2163|
1746 or 1365 or 593
— to —
1747 or 1366 or 594
|Wikimedia Commons has media related to 1620.|
1620 (MDCXX) was a leap year starting on Wednesday of the Gregorian calendar and a leap year starting on Saturday of the Julian calendar, the 1620th year of the Common Era (CE) and Anno Domini (AD) designations, the 620th year of the 2nd millennium, the 20th year of the 17th century, and the 1st year of the 1620s decade. As of the start of 1620, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.
- February 4 – Prince Bethlen Gabor signs a peace treaty with Ferdinand II, Holy Roman Emperor.
- May 17 – The first merry-go-round is seen at a fair (Philippapolis, Turkey).
- June 3 – The oldest stone church in French North America, Notre-Dame-des-Anges, is begun at Quebec City, Canada.
- July 3 – Under the terms of the Treaty of Ulm, the Protestant Union declares neutrality, and ceases to support Frederick V of Bohemia.
- July 15 – The ship Speedwell departs Delfshaven, with the Leiden colonists and Pilgrims.
- August 15 (August 5 Old Style) – Mayflower and Speedwell depart together from Plymouth, England, but Speedwell starts to leak again and must stop.
- August 7
- September 16 (September 6 Old Style) – Mayflower departs from Plymouth, England, on its third attempt without Speedwell, arriving on November 11 (Old Style date) at Cape Cod (named from the Concord voyage of 1602).
- September 17–October 7 – Battle of Cecora: The Ottoman Empire defeats Polish���Lithuanian Commonwealth–Moldavian troops.
- October 6 – Battle of Amedamit in Gojjam, Ethiopia: The Roman Catholic Ras Sela Kristos, half-brother of Emperor Susenyos, crushes a group of rebels, who were opposed to Susenyos' pro-Catholic beliefs.
- November 3 – The Great Patent is granted to Plymouth Colony.
- November 8 – Thirty Years' War – Battle of White Mountain: Catholic forces are victorious in only two hours near Prague.
- November 11 – The Mayflower Compact is signed in what is now Provincetown Harbor near Cape Cod.
- November 21 (November 11 O.S.) – The Mayflower arrives inside the tip of Cape Cod, at what becomes known as Provincetown Harbor, with the Pilgrims and Planters; 41 Plymouth Colony settlers sign the Mayflower Compact, the first governing document of the colony, onboard the ship.
- November 25 – The Wedding of Gustav II Adolf and Maria Eleonora takes place.
- December 21 – Plymouth Colony: William Bradford and the Mayflower Pilgrims land on what becomes known as Plymouth Rock, in Plymouth, Massachusetts.
- A severe frost in England, freezes the Thames River; 13 continuous days of snow blanket Scotland. On Eskdale Moor, only 35 of a flock of 20,000 sheep survive.
- Francis Bacon publishes the Novum Organum (beyond Aristotle's Organon) on logical thinking.
- Two officers of the British East India Company attempt to claim the Table Mountain region (in present-day South Africa) for England, but fail.
- Shōgun Tokugawa Hidetada restores Osaka Castle. Its current appearance dates from this remodeling.
- The modern violin is developed.
- Witch hunts begin in Scotland.
- Cornelis Drebbel, at the Thames, builds an undersea boat (history of submarines).
- Juan Pablo Bonet, teacher of deaf children in the Spanish court, creates the sign alphabet.
- The Thirty Years' War (1618–1648) continues (principally on the territory of today's Germany).
- A Short Account of the Destruction of the Indies by Bartolomé de las Casas and Origin and progress of the disturbances in the Netherlands by Johannes Gysius is re-published in the Netherlands.
- January 1
- January 5 – Miklós Zrínyi, Croatian military commander (d. 1664)
- January 9 – Anton Günther I, Count of Schwarzburg-Sondershausen (d. 1666)
- January 17 – Anton Janson, Dutch type founder and printer (d. 1687)
- January 31 – Prince Georg Friedrich of Waldeck, Dutch general and German field marshal (d. 1692)
- February 1 – Gustaf Bonde, Swedish politician (d. 1667)
- February 3 – Sir James Clavering, 1st Baronet, English landowner (d. 1702)
- February 5 – Paul Barbette, Dutch physician (d. 1666)
- February 13 – Girolamo Casanata, Italian cardinal (d. 1700)
- February 15 – François Charpentier, French archaeologist and man of letters (d. 1702)
- February 16 – Frederick William, Elector of Brandenburg (d. 1688)
- February 23 – Francis Newport, 1st Earl of Bradford, English politician (d. 1708)
- March 10 – Johann Heinrich Hottinger, Swiss philologist and theologian (d. 1667)
- March 13 – Alexander Seton, 1st Viscount of Kingston (d. 1691)
- March 29 – Edward Digges, English barrister and colonist, Colonial Governor of Virginia (d. 1674)
- April 4 – Bernardino León de la Rocha, Roman Catholic prelate, Bishop of Coria and of Tui (1669–1673) (d. 1675)
- April 15 – Edward Villiers, English politician and military officer (d. 1689)
- April 17 – Marguerite Bourgeoys, French Catholic nun, founder of the Congregation of Notre Dame (d. 1700)
- April 18 – Winston Churchill (1620–1688), English noble, soldier (d. 1688)
- April 21 – Salvatore Castiglione, Italian painter (d. 1676)
- April 24 – John Graunt, English demographer (d. 1674)
- May 3 – Bogusław Radziwiłł, Polish-Lithuanian noble (d. 1669)
- May 21 – Krsto Zmajević, Montenegrin-born Venetian merchant (d. 1688)
- May 23 – Pieter Neefs the Younger, Flemish painter (d. 1675)
- May 25 – Warwick Mohun, 2nd Baron Mohun of Okehampton, English Member of Parliament (d. 1665)
- June 6 – Sir John Covert, 1st Baronet, English politician (d. 1679)
- June 11 – John Moore (Lord Mayor), Member of Parliament for the City of London (d. 1702)
- July 20
- July 21 – Jean Picard, French astronomer and priest (d. 1704)
- July 31 – Juan Ignacio de la Carrera Yturgoyen, Chilean politician (d. 1682)
- August 6 – William Hiseland, English (later British) soldier, reputed supercentenarian (d. 1732)
- August 19 – Johann Just Winckelmann, German writer and historian (d. 1699)
- August 22 – Alexander Rigby (died 1694), English politician (d. 1694)
- August 24 – Thomas Stucley (MP), English politician (d. 1663)
- August 26 – Ernst Bogislaw von Croÿ, German Lutheran administrator (d. 1684)
- September 4 – Ernest Gottlieb, Prince of Anhalt-Plötzkau (d. 1654)
- September 6 – Isabella Leonarda, Italian composer (d. 1704)
- September 18 – Albert II, Margrave of Brandenburg-Ansbach, German prince (d. 1667)
- September 25 – François Bernier, French physician and traveller (d. 1688)
- September 29 – John Louis of Elderen, Bishop of Liege (d. 1694)
- October 1 – Nicolaes Pieterszoon Berchem, Dutch Golden Age painter of pastoral landscapes (d. 1683)
- October 4 – François-Henri Salomon de Virelade, French lawyer (d. 1670)
- October 15 – William Borlase (died 1665), English politician (d. 1665)
- October 16 – Pierre Paul Puget, French painter (d. 1694)
- October 20 – Aelbert Cuyp, Dutch painter (d. 1691)
- October 27 – Philip Louis, Duke of Schleswig-Holstein-Sonderburg-Wiesenburg (d. 1689)
- October 31 – John Evelyn, English diarist and writer (d. 1706)
- November 10
- c. November 20 – Peregrine White, first child born to English settlers at Plymouth Colony (d. 1704)
- December 17
- December 18 – Heinrich Roth, German Jesuit missionary, pioneering Sanskrit scholar (d. 1668)
- December 23 – Johann Jakob Wepfer, Swiss pathologist (d. 1695)
- January 23 – John Croke, English politician and judge (b. 1553)
- January 26 – Amar Singh I, ruler of Mewar (b. 1559)
- January 28 – Archduchess Eleanor of Austria (b. 1582)
- February 15 – James Archer, Irish Jesuit; played a controversial role in the Nine Years' War (b. 1550)
- February 19
- February 23 – Nicholas Fuller, English politician (b. 1543)
- March 1 – Thomas Campion, English poet and composer (b. 1567)
- March 5 – Giovanni Francesco Sagredo, Italian mathematician (b. 1571)
- March 17 – St. John Sarkander, Moravian priest (injuries caused by torturing) (b. 1576)
- March 25 – Johannes Nucius, German composer (b. c. 1556)
- March 29 – Hachisuka Yoshishige, Japanese daimyō of the Edo period (b. 1586)
- April 8 – Angelo Rocca, Italian humanist (b. 1545)
- April 23 – Hayyim ben Joseph Vital, Palestinian-born Kabbalist (b. 1543)
- April 14 – Rascas de Bagarris, French scholar (b. 1562)
- May 16 – William Adams, English navigator and samurai (b. 1564)
- May 30 – Mathias Hovius, Roman Catholic archbishop (b. 1542)
- June 17 – Mikołaj Zebrzydowski (b. 1553)
- July 13 – William Louis, Count of Nassau-Dillenburg (b. 1560)
- August 2 – Carolus Luython, Belgian composer (b. 1557)
- August 14 – Katherine Hastings, Countess of Huntingdon, wife of Henry Hastings, 3rd Earl of Huntingdon (b. 1540)
- August 18 – Wanli Emperor, of China (b. 1563)
- September 13 – Wolfgang Hirschbach, German legal scholar (b. 1570)
- September 26 – Taichang Emperor, fourteenth emperor of the Ming dynasty of China (b. 1582)
- September – Sidonia von Borcke, German noble and alleged witch (b. 1548)
- October 7 – Stanisław Żółkiewski, Polish nobleman of the Lubicz coat of arms (b. 1547)
- November 6 – Philip III, Margrave of Baden-Rodemachern (1588–1620) (b. 1567)
- November 7 – Robert Hesketh, English politician (b. 1560)
- November 9 – Louise de Coligny, daughter of Gaspard II de Coligny; fourth and last spouse of William the Silent (b. 1555)
- November 11 – Isaac and Josias Habrecht, Swiss watchmaking brothers (b. 1544)
- November 27 – Francis, Duke of Pomerania-Stettin, Bishop of Cammin (b. 1577)
- December 3 – Janusz Radziwiłł, Polish noble (b. 1579)
- December 21 – George Fleetwood, English politician (b. 1564)
- Rose of Turaida, legendary Latvian murder victim (b. 1601)
- John Flower, English politician (b. 1535)
- Stratton, J.M. (1969). Agricultural Records. John Baker. ISBN 0-212-97022-4.
- "Mirror of the Cruel and Horrible Spanish Tyranny Perpetrated in the Netherlands, by the Tyrant, the Duke of Alba, and Other Commanders of King Philip II". World Digital Library. 1620. Retrieved August 25, 2013.
- Pavel, Lilia Zabolotnaia (2012). "The Story of the Courtship of Catherine 'the Circassian', the Second Wife of the Prince Vasile Lupu" (PDF). Codrul Cosminului. 18 (1): 43–50. Retrieved April 29, 2015.
- Inachim, Kyra (2008). "Herrschaft der letzten Greifengeneration". Die Geschichte Pommerns (in German). Rostock: Hinstorff. ISBN 978-3-356-01044-2.