Ban Ki-Moon served as the 8th Secretary-General of the United Nations from 2007 to 2016. The sequence was: Trygve Lie (1st), Dag Hammarskjöld (2nd), U Thant (3rd), Kurt Waldheim (4th), Javier Pérez de Cuéllar (5th), Boutros Boutros-Ghali (6th), Kofi Annan (7th), and then Ban Ki-Moon (8th).