Héctor-Neri Castañeda (December 13, 1924 – September 7, 1991) was a Guatemalan philosopher and founder of the journal Noûs.Born in San Vicente, Zacapa, Guatemala, he emigrated to the United States in 1948 and studied under Wilfrid Sellars at the University of Minnesota, where he earned a B.A. in 1950 and M.A. in 1952. Castañeda received his Ph.D. in June 1954 for his dissertation "The Logical Structure of Moral Reasoning". He studied at Oxford University from 1955–1956, after which he once again returned to the US to take a sabbatical-replacement position in philosophy at Duke University. Castañeda is noted for his development of Guise theory, which he applied to outstanding problems in the analysis of thought, language, and the structure of the world. He is also credited with the discovery of the "quasi-indicator" or "quasi-indexical", a linguistic device by which one person can attribute an indexical reference to another. His discussion on this matter strongly influenced John Perry's theory of indexicals, an influence which Perry acknowledged in the first footnote of the paper "The Problem of the Essential Indexical".He died of a brain tumor in 1991.