1665

January–June

• January 5 - The Journal des sçavans begins publication in France, the first scientific journal.
• March 4 - The Second Anglo-Dutch War begins.
• March 6 - The Philosophical Transactions of the Royal Society of London begins publication in England, the first scientific journal in English and the oldest to be continuously published.
• March 11 - A new legal code is approved for the Dutch and English towns of New York, guaranteeing all Protestants the right to continue their religious observances unhindered.
• March 16 - Bucharest allows Jews to settle in the city, in exchange for an annual tax of 16 guilders.
• April 12 - Margaret Porteous is the first person recorded to die in the Great Plague of London. This last major outbreak of Bubonic plague in the British Isles has possibly been introduced by Dutch prisoners of war. Two-thirds of Londoners leave the city, but over 68,000 die. The plague spreads to Derbyshire.
• May 19 - Great fire of Newport, Shropshire, England.
• June 12 - England installs a municipal government in New York City.
• June 13 - Second Anglo-Dutch War: The English naval victory at the Battle of Lowestoft under James Stuart, Duke of York.
• June 30 - King Charles II of England issues a second charter for the Province of Carolina, which clarifies and expands the borders of the Lords Proprietors' tracts.

  July–December

• July 3 - The first documented case of cyclopia is diagnosed in a horse.
• July 7 - King Charles II of England leaves London with his entourage, fleeing the Great Plague. He moves his court to Salisbury, then Exeter.
• August - The Great Plague forces the closure of the University of Cambridge, where Isaac Newton is a student. Newton retires to his home in Lincolnshire for safety, and stays there for two years. During that time alone, Newton will make groundbreaking discoveries in mathematics, calculus, mechanics, and optics, and lay the foundations for his books Philosophiæ Naturalis Principia Mathematica and Optiks.
• August 2 - Second Anglo-Dutch War: The Dutch fleet defeats the English in the Battle of Vågen.
• August 27 - Ye Bare & Ye Cubbe, the first play in English in the American colonies, is performed in Pungoteague, Virginia.
• September - Robert Hooke's Micrographia is published in London, first applying the term 'cell' to plant tissue, which he discovered first in cork, then in living organisms, using a microscope.
• September 17 - Charles II of Spain becomes king, while not yet four years old.
• September 22 - Molière's L'Amour médecin is first presented, before Louis XIV of France, at the Palace of Versailles, with music by Jean-Baptiste Lully.
• October 5 - The University of Kiel is founded.
• October 21 - Louis XIV of France and Jean-Baptiste Colbert found the Manufacture royale des glaces of Saint Gobain, which is the oldest French company of the CAC 40, with 350 years in 2015.
• October 29 - Battle of Mbwila: Portuguese forces defeat and kill King António I of Kongo.
• November 7 - The London Gazette is first published as The Oxford Gazette.
• December 10 - The Royal Netherlands Marine Corps is founded by Michiel de Ruyter.

  Date unknown

• The Colonisation of Réunion begins, with the French East India Company sending twenty settlers.
• Ferdinando Carlo Gonzaga is invested as Duke of Mantua.
• Joan Blaeu completes publication of his Atlas Maior in Amsterdam.
• John Bunyan publishes The End of the World, The Resurrection of the Dead and Eternal Judgment and The Holy City or the New Jerusalem.
• English poet John Milton popularizes the Chinese sailing carriage in a famous poem; this peculiar Chinese invention was first written of in the West by Abraham Ortelius, in his atlas of 1584.