Hans Martin Blix (help·info) (born 28 June 1928 in Uppsala, Sweden) is a Swedish diplomat and politician. He was Swedish Minister for Foreign Affairs (1978 - 1979). Blix was also the head of the United Nations Monitoring, Verification and Inspection Commission from March 2000 to June 2003, when he was succeeded by Demetrius Perricos. In 2002, the commission began searching Iraq for weapons of mass destruction, ultimately finding none. He is the son of professor Gunnar Blix and Hertha Wiberg and grandson of professor Magnus Blix. He comes from a family of Jamtlandic origin.

Blix studied at Uppsala University and Columbia University, earning his Ph.D. from the University of Cambridge (Trinity Hall). In 1959, he became a Juris Doctor in International Law at the University of Uppsala, where he was appointed Associate Professor in International Law the next year.

Between 1962 and 1978 Blix was a member of the Swedish delegation at the Disarmament Conference in Geneva. He held several other positions in the Swedish administration between 1963 and 1976, and from 1961 to 1981 served on the Swedish delegation to the United Nations. From 1978 to 1979, Blix was the Swedish Foreign Minister.