John Albert Leach (19 March 1870 – 3 October 1929) was an ornithologist, teacher and headmaster in the state of Victoria, Australia. Leach was born in Ballarat, Victoria and educated at Creswick Grammar School (where he was dux), Melbourne Training College (1890) and the University of Melbourne, where he graduated B.Sc. in 1904, M.Sc. in 1906 and in 1912 obtained his doctorate for research in ornithology. Among his contributions to ornithology was the relationship between the Australian magpie, butcherbirds and currawongs in the family Cracticidae, now sunk as a subfamily into Artamidae.