There is no UN president, the head of th UN is callled the "General Secretary"

These are the people who have been UNGS:

Gladwyn Jebb (United Kingdom) 1945 - 1946

Tryge Lie (Norway) 1946 - 1952

Dag Hammarsskjold (Sweden) 1953 -1961

U Thant (Burma) 1961 - 1971

Kurt Waldheim (Austria) 1972 - 1981

Javier Perez de Cuellar (Peru) 1982 -1991

Butros Butos-Gahli (Egypt) 1992 -1996

Kofi Annan (Ghana) 1997 - 2006

Ban Ki-moon (South Korea) 2007 - Present