Brigadier William Harry Evans CSI CIE DSO (born 22 July 1876 in Shillong – died 13 November 1956, Church Whitfield ) was a lepidopterist and British Army officer who served in India.

He documented the butterfly fauna of India, Burma and Ceylon in a series of articles in the Journal of the Bombay Natural History Society.

Evans, however, stayed in London to complete his Revision of the Hesperiidae of the world, as he stated "before he died".

His favourite collection areas included Kodaikanal, Jabalpur, Simla, Murree, Darjeeling, Chitral and Baluchistan.

From 1923 he published keys to the identification of Indian butterflies in the Journal of the Bombay Natural History Society.

Evans was influenced by the works of Bernhard Rensch, Ernst Mayr and Thomas Huxley, but he was not comfortable with the ideas of phylogenetic classification.