Among the candidates are Costa Rica's Rebeca Grynspan, Argentina's Rafael Grossi, Chile's Michelle Bachelet, Ecuador's María Fernanda Espinosa and Yvonne A-Baki, Guyana's Carolyn Rodrigues-Birkett, Uganda's Olara Otunnu, and Senegal's Macky Sall.

The UN Security Council's 15 members will nominate one from among the candidates. He or she will then take office as Secretary-General after approval by the General Assembly. However, the candidate must receive at least nine votes and also avoid a veto from any of the Security Council's five permanent members.

Among the candidates, Rebeca Grynspan currently serves as the head of the UN Conference on Trade and Development (UNCTAD). Rafael Grossi is the head of the International Atomic Energy Agency (IAEA). Michelle Bachelet is a former president of Chile and former UN human rights chief.

Meanwhile, María Fernanda Espinosa is a former president of the UN General Assembly. Carolyn Rodrigues-Birkett is Guyana's former foreign minister, Yvonne A-Baki is an Ecuadorian diplomat, Macky Sall is a former president of Senegal, and Olara Otunnu is a former senior UN official.

Ultimately, who will lead the UN depends on the Security Council vote and the support of the permanent member countries.