Oscar Lorenzo Fernández (4 November 1897 – 27 August 1948) was a Brazilian composer of Spanish descent. He was born and died in Rio de Janeiro.Fernández studied at the Instituto Nacional de Música with Francisco Braga, Frederico Nascimento, and Henrique Oswald. In 1923, Nascimento was taken seriously ill, and Fernández was designated his temporary substitute in the chair of upper-level harmony, an appointment which became permanent two years later. In 1936 he founded the Conservatório Brasileiro de Música in Rio de Janeiro, which he directed until his death. From 1939 onward, he also served as Professor of Choral Singing at the Conservatório Nacional de Canto Orfeônico.