1673 (MDCLXXIII) was a common year starting on Sunday of the Gregorian calendar and a common year starting on Wednesday of the Julian calendar, the 1673rd year of the Common Era (CE) and Anno Domini (AD) designations, the 673rd year of the 2nd millennium, the 73rd year of the 17th century, and the 4th year of the 1670s decade. As of the start of 1673, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.

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• January 31 – St. Louis Maria Grignion de Montfort, French missionary priest (d. 1716)
• April 27 – Claude Gillot, French artist (d. 1722)
• July 20 – John Dalrymple, 2nd Earl of Stair, Scottish soldier and diplomat (d. 1747)
• August 8 – John Ker, Scottish informer (d. 1726)
• August 10 – Johann Konrad Dippel, German alchemist (d. 1734)
• August 11 – Richard Mead, English physician (d. 1754)
• August 18 – Louise Élisabeth de Joybert, politically active Canadian governors' wife (d. 1740)
• October 26 – Dimitrie Cantemir, Moldavian linguist and scholar (d. 1723)
• December 30 – Ahmed III, Ottoman Sultan (d. 1736)

• January 11 – Bartholomew Mastrius, Italian theologian (b. 1602)
• January 22 – Mary Carleton, Englishwoman who used false identities (b. 1642)
• January 26 – Jérôme Lalemant, French Jesuit priest and missionary to Canada (b. 1593)
• February 2 – Kaspar Förster, German singer and composer (b. 1616)
• February 12, – Johann Philipp von Schönborn, Archbishop-Elector of Mainz (1647– (b. 1605)
• February 17 – Molière, French writer and actor (b. 1622)
• February 22 – Anna Magdalene of Hanau, German countess (b. 1600)
• March 6 – Isaack Luttichuys, Dutch Golden Age painter (b. 1616)
• March 12 – Margaret Theresa of Spain (b. 1651)
• March 15 – Salvator Rosa, Italian painter and poet (b. 1615)
• March 20
  • Anna Margareta von Haugwitz, Swedish countess (b. 1622)
  • Augustyn Kordecki, Polish prior (b. 1603)
• April 21 – Ignace-Gaston Pardies, French physicist (b. 1636)
• May 14 – Sir Gerrard Napier, 1st Baronet, English politician (b. 1606)
• May 6 – Werner Rolfinck, German physician, chemist, botanist, philosopher (b. 1599)
• May 9 – Jacques Vallée, Sieur Des Barreaux, French poet (b. 1599)
• May 27 – Henry Hungerford, English politician (b. 1611)
• May 30 – Sir Edward Bagot, 2nd Baronet, English politician (b. 1616)
• June 6 – Eugene Maurice, Count of Soissons, Italian noble (b. 1635)
• June 18 – Jeanne Mance, French Canadian settler (b. 1606)
• June 28 – Johan Schatter, Dutch member of the Haarlem schutterij (b. 1594)
• June 25 – Charles de Batz-Castelmore d'Artagnan, French soldier (b. 1611)
• July 4 – Robert Moray, English Freemason (b. 1608 or 1609)
• July 15 – Helena Fourment, Dutch model, second wife of Peter Paul Rubens (b. 1614)
• August 17 – Regnier de Graaf, Dutch physician and anatomist (b. 1641)
• August 21
  • Henry Grey, 1st Earl of Stamford, English soldier (b. c. 1599)
  • Daniel Pawłowski, Polish writer (b. 1627)
  • Isaac Sweers, Dutch admiral (b. 1622)
• August 25 – Bartram de Fouchier, Dutch painter (b. 1609)
• September 6 – Jan Thomas van Ieperen, Flemish engraver and painter (b. 1617)
• September 21 – Lorenzo Imperiali, Italian cardinal (b. 1612)
• October 5 – Francesco Grue, Italian artist (b. 1618)
• October 13 – Christoffer Gabel, Danish statesman (b. 1617)
• October 17 – Thomas Clifford, 1st Baron Clifford of Chudleigh, English statesman (b. 1630)
• November 6 – Robert Harley, English politician (b. 1626)
• November 10 – Michał Korybut Wiśniowiecki, King of Poland (b. 1640)
• November 17 – Thomas Wendy, English politician (b. 1614)
• November 29 – Armand de Gramont, Comte de Guiche, French nobleman (b. 1637)
• December 15 – Margaret Cavendish, English writer (b. 1623)
• December 21 – Joan Blaeu, Dutch cartographer (b. 1596)
• December 29 – Manuel da Câmara III, Portuguese noble (b. 1630)
• December 31 – Oliver St John, English statesman and judge (b. c. 1598)