The Secretary-General of the United Nations (UN) is the head of the UN Secretariat. The role of the secretary-general is prescribed by the UN Charter, the founding document of the United Nations, as well as by accepted practice and various procedural rules. The interpretation of these provisions by the eight secretary-generals to date (from 1946 until 2015) has greatly varied. According to the UN Charter, the Secretary General is the United Nation’s “chief administrative officer.” The UN website explains that the secretary-general is “equal parts diplomat and advocate, civil servant, and CEO.” The first secretary-general, the Norwegian Trygve Lie, was said to have told his successor, Dag Hammarskjöld, “You are about to enter the most impossible job on this earth.”