Onil (Valencian: [oˈnil], Spanish: [oˈnil]) is a town located in the comarca of L'Alcoià, in the province of Alicante, Spain. It has an area of 48.41 km2 and, according to the 2006 census, a total population of 7466 inhabitants and a population density of 154.22 inhabitants/km2. Onil is located next to the mountain called Sierra de Onil in the Sierra de Mariola, 36 km from Alicante city.