Special Envoy of the Secretary-General
Special Envoy of the Secretary-General (SESG) is a title used by certain United Nations officials who are appointed by the Secretary-General of the United Nations to deal with specific issues. Examples include the SESGs on HIV/AIDS in Africa, on LRA-affected areas, on indigenous people, to a specific country, et cetera.
Source: Wikipedia — Special Envoy of the Secretary-General (CC BY-SA 4.0)