Ernesto Samper Pizano is a Colombian politician. Samper is a member of the influential Samper family. He served as the President of Colombia from 1994 to 1998, representing the Liberal Party. From 2014 to 2017 he served as the Secretary General of the Union of South American Nations (UNASUR).

The Union of South American Nations (USAN), sometimes also referred to as the South American Union, abbreviated in Spanish as UNASUR and in Portuguese as UNASUL, is an intergovernmental regional organization set up by Hugo Chavez to counteract the influence of the United States in the region. It once comprised twelve South American countries; as of 2019, most have withdrawn.