1666 in Denmark

Events from the year 1666 in Denmark.

Incumbents

 * Monarch – Frederick III

Events

 * 11 February; Denmark agrees an offensive alliance with the Dutch Republic against England, and enters the Second Anglo-Dutch War;
 * 1 August – Anders Bording's Den Danske Mercurius, Denmark's first newspaper, is published for the first time.

Undated

 * Holmen Cemetery, the oldest cemetery in Denmark still in use, relocates to its current location in Østerbro

Births

 * 22 February – Christian Christophersen Sehested, nobleman (died 1740)
 * 16 June – Johan Conrad Ernst, architect (died 1750)

Deaths

 * 23 September – Hannibal Sehested, diplomat (born 1609)
 * 30 October – Iver Krabbe, nobleman and military officer (born 1602)