Year 1661 (MDCLXI) was a common year starting on Saturday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Tuesday of the 10-day slower Julian calendar).

Events of 1661

• January 6 - The Fifth Monarchists unsuccessfully attempt to seize control of London. George Monck's regiment defeats them.
• January 30 - The body of Oliver Cromwell is exhumed and subjected to a posthumous execution, along with those of John Bradshaw and Henry Ireton.
• February 5 - The Shunzhi Emperor of the Qing Dynasty of China dies and is succeeded by his son the Kangxi Emperor.
• February 14 - George Monck’s regiment becomes The Lord General's Regiment of Foot Guards (which later becomes Coldstream Guards)
• March - Following the death of his mentor, Cardinal Mazarin, King Louis XIV of France starts to rule independently.
• April 23 - King Charles II of England, Scotland, Ireland is crowned in Westminster Abbey, for the second time.
• July 1 - Russo-Swedish War (1656–1658) - Treaty of Cardis: Russia surrenders to Sweden all captured territories.

• August 6 - Portugal and the Dutch Republic sign the Treaty of The Hague, whereby New Holland is formally ceded to Portugal by the Dutch Republic.

Undated

• Dutch rule ends in Taiwan.
• The first modern bank notes are issued in Stockholm, Sweden.
• Köprülü Mehmed Pasha ends his rule as vizier of the Ottoman Empire.

Births

• January 30 - Charles Rollin, French historian (d. 1741)
• March 25 - Paul de Rapin, French historian (d. 1725)
• April 16 - Charles Montagu, 1st Earl of Halifax, English poet and statesman (d. 1715)
• May 25 - Claude Buffier, French philosopher and historian (d. 1737)
• June 9 - Tsar Feodor III of Russia (d. 1682)
• July 20 - Pierre Le Moyne d'Iberville, French founder of the colony of Louisiana (d. 1706)
• September 2 - Georg Böhm, German organist (d. 1733)
• October 11 - Melchior de Polignac, French diplomat (d. 1742)
• November 1 - Florent Carton Dancourt, French dramatist and actor (d. 1725)
• November 4 - Karl III Philip, Elector Palatine (d. 1742)
• November 6 - King Charles II of Spain (d. 1700)
• November 15 - Christoph von Graffenried, Swiss settler in America (d. 1743)
• November 28 - Edward Hyde, 3rd Earl of Clarendon, British Governor of New York and New Jersey (d. 1723)
• December 5 - Robert Harley, 1st Earl of Oxford and Mortimer, English statesman (d. 1724)
• December 18 - Christopher Polhem, Swedish scientist and inventor (d. 1751)

Deaths

• January 19 - Thomas Venner, Fifth Monarchist (executed)
• February 2 - Lucas Holstenius, German humanist (b. 1596)
• February 5 - Shunzhi Emperor of China (b. 1638)
• March 1 - Richard Zouch, English jurist (b. 1590)
• March 9 - Jules Cardinal Mazarin, French cardinal and statesman (b. 1602)
• April 4 - Alexander Leslie, 1st Earl of Leven, Scottish soldier(b. c. 1580)
• April 7 - William Brereton, English soldier and politician (b. 1604)
• May 27 - Archibald Campbell, 1st Marquess of Argyll, Scottish dissenter (beheaded) (b. 1607)
• August 7 - Jin Shengtan, Chinese editor, writer and critic (b. 1608)
• August 16 - Thomas Fuller, English churchman and historian (b. 1608)
• October 4 - Jacqueline Pascal, French child prodigy and sister of Blaise Pascal (b. 1625)
• October 28 - Agustín Moreto y Cavana, Spanish playwright (b. 1618)
• November 19 - Brian Walton, English clergyman and scholar (b. 1600)
• December 29 - Antoine Gérard de Saint-Amant, French poet (b. 1594)