Goeldi's marmoset, or Goeldi's monkey, is a small New World monkey found on the South American continent, mainly in the upper Amazon basin of Bolivia, Brazil, Colombia, and Perú. It is the only species classified in the monotypic genus Callimico, thus these monkeys are sometimes referred to as "callimicos". The species takes its name from its discoverer, Swiss-Brazilian naturalist Emil August Goeldi.

Émil August Goeldi, was a Swiss-Brazilian naturalist and zoologist. He was the father of Oswaldo Goeldi, a noted Brazilian engraver and illustrator.