Acin is a surname. Notable people with the surname include:
Andrej Aćin (born 1972), Serbian director Ramón Acín (1888–1936), Spanish anarcho-syndicalist Acin may also refer to Acín, an inhabited village in Jaca, in the province of Huesca, in Spain.
See also Asociación de Cabildos Indígenas del Norte del Cauca, Colombian indigenous rights organization ac.in, second-level domain used for universities in India