← 1665 1664 1663 1666 in Denmark → 1667 1668 1669
Decades:	1640s 1650s 1660s 1670s 1680s
See also:	Other events of 1666 List of years in Denmark

Events from the year 1666 in Denmark.

Incumbents

• Monarch – Frederick III^[1]

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)