Willem Werner Hubert "Willy" Claes[1] (Dutch: [ˈʋɪli ˈklaːs]; born 24 November 1938) is a Belgian politician who served as the eighth Secretary General of NATO, from 1994 to 1995.

Claes was forced to resign from his NATO position after he was found guilty of corruption, which was uncovered during the investigation into André Cools' death.

Claes was Minister of Foreign Affairs from 1992 until 1994 in the Government Jean-Luc Dehaene I, during which period he presided over Belgium's withdrawal from the UN peacekeeping mission in Rwanda during the Rwandan genocide.

[3] Claes was also Secretary General of NATO from 1994 until 1995, when he resigned after the discovery of a bribe of over 50 million Belgian francs (BEF), accepted at the time he was minister of economic affairs and connected to the defence contract negotiations with Agusta and Dassault.

Claes received a 60 000 BEF fine, a three-year probationary sentence and a five-year prohibition on running for public office.