Big Hill is a bounded rural locality in Upper Lachlan Shire to the north of Marulan in the Southern Tablelands of New South Wales, Australia. At the 2016 census, it had a population of 44. The area is characterised with agricultural activities, predominantly grazing, as well as National Parks. Grazing was first introduced by Hannibal Hawkins Macarthur nephew of John Macarthur, who established a 1000 acre farm, Arthursleigh, at Big Hill in 1819. Big Hill Post Office opened on 1 November 1869 and closed in 1945.