Sir Walter Kieran Prendergast KCVO CMG (born 2 July 1942) is a British retired diplomat who was Under-Secretary-General for Political Affairs at the United Nations.
Prendergast was born in Campbeltown, Scotland, and received his education at St Patrick's College, Strathfield in Sydney, Australia. He later went to England and attended Salesian College in Chertsey and then St Edmund Hall, Oxford.
After graduation, Prendergast was a Turkish language student with the FCO in Istanbul 1964-65, after which he joined the British Embassy in Ankara, Turkey for two years, until 1967, when he was posted to the NATO Department at the British Foreign Office. He later worked with the foreign service in Nicosia, Cyprus, and The Hague. In 1976, he returned to London as Assistant Private Secretary to Anthony Crosland and David Owen, Secretaries of State for Foreign and Commonwealth Affairs. From 1979 to 1982, Prendergast worked in New York with Anthony Parsons as part of the United Kingdom Mission to the United Nations. In 1982, he was appointed Head of Chancery and Consul-General in Tel Aviv, Israel and worked there for four years, later serving as High Commissioner to Zimbabwe and Kenya, before returning to Ankara, this time as Ambassador to Turkey.