Henrik Kauffmann (26 August 1888 – 5 June 1963) was the Danish ambassador to the United States during World War II.
On 9 April 1941, the anniversary of the German occupation of Denmark, he signed on his own initiative "in the Name of the King" (Danish: I Kongens Navn) an "Agreement relating to the Defense of Greenland" authorizing the United States to defend the Danish colonies on Greenland from German aggression. The treaty was signed by the United States Secretary of State Cordell Hull and approved by President Franklin D. Roosevelt on 7 June 1941.
Kauffmann's treaty was approved by the local officials on Greenland but declared void by the Danish government in Copenhagen. Kauffmann ignored this protest citing that Denmark was occupied by a hostile power, consequently, he considered the government to be unable to protect Danish interests. The government responded by charging Kauffmann with high treason and stripping him of his rank. Kauffmann ignored both actions. Kauffmann's line was supported by the Danish consuls general in the United States, as well as by the Danish ambassador to Iran. These diplomats were dismissed as well. Kauffmann replied by urging Danish diplomats around the world not to follow instructions from Copenhagen.
Kauffmann was nicknamed "the King of Greenland" for his independent political moves in the Greenland affair.
He was married to Charlotte MacDougall, the daughter of United States Navy Rear Admiral William D. MacDougall.
Revoking the sentence against Kauffmann was one of the first tasks done by the Danish Parliament following the Liberation of Denmark in May 1945. Kauffmann joined the Cabinet of National Unity and served as Minister without Portfolio from 12 May to 7 November 1945.
Kauffmann's treaty was adapted in the early 1950s and remains the legal basis for the U.S. Thule Air Base in Greenland.
In June 1963, Kauffmann, suffering from prostate cancer, was killed by his wife in a "mercy killing". His wife, Charlotte, then took her own life.