U Thant was a Burmese diplomat and the third Secretary-General of the United Nations, from 1961 to 1971. He was chosen for the post when his predecessor Dag Hammarskjöld was killed in an air crash in September 1961. 'U' is an honorific in Burmese, roughly equal to 'Mister'. Thant was his only name. In Burmese he was known as Pantanaw U Thant, a reference to his home town of Pantanaw. Wikipedia
U Thant, who served as Secretary-General of the United Nations from 1961 to 1971, was chosen to head the world body when Secretary-General Dag Hammarskjold was killed in an air crash in September 1961. www.un.org/Overview/SG/sg3bio.html
The definitive Wikipedia entry for U Thant. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/U_Thant