1690 (MDCXC) was a common yearstarting on Sunday of the Gregorian calendarand a common year starting on Wednesday of the Julian calendar, the 1690th year of the Common Era (CE) and Anno Domini (AD) designations, the 690th year of the 2ndmillennium, the 90th year of the 17thcentury, and the 1st year of the 1690s decade. As of the start of 1690, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.

• January 6 – Joseph, son of Emperor Leopold I becomes King of the Romans
• January 14 – The clarinet is invented in Nuremberg, Germany
• May 20 – England passes Act of Grace, forgiving followers of James II
• July 1 – The Battle of the Boyne, in Ireland
• October 6-12 – Massachusetts Puritans led by Sir William Phips besiege the city of Quebec. The siege ends in failure.
• December 29 – earthquake in Anconer in Papal States, Italy

• Earliest recorded sighting of the planet Uranus, by John Flamsteed, who mistakenly catalogues it as the star 34 Tauri
• Giovanni Domenico Cassini observes differential rotation within Jupiter's atmosphere.
• The French invade the small town of Teignmouth in Southwest England, in their last attack on England.

• January 22 – Nicolas Lancret, French painter (d. 1743)
• February 1 – Francesco Maria Veracini, Italian composer (d. 1768)
• February 3 – Richard Rawlinson, English minister and antiquarian (d. 1755)
• March 18 – Christian Goldbach Prussian mathematician (d. 1764)
• April 22 – John Carteret, 2nd Earl Granville, English statesman (d. 1763)
• September 12 – Peter Dens, Belgian Catholic theologian (d. 1775)
• October 29 – Martin Folkes, English antiquarian (d. 1754)
• November 24 – Charles Theodore Pachelbel, German composer (d. 1750)
• November 29 – Christian Augustus of Anhalt-Zerbst, father of Catherine II of Russia (d. 1747)
• December 1 – Philip Yorke, 1st Earl of Hardwicke, Lord Chancellor of England (d. 1764)