Edward Denny Day, also known as Denny Day, was a police magistrate, and the son of a clergyman of the Church of England in Country Kerry, Ireland. In the early 1800s, Day enlisted in the 46th Regiment as an ensign and by 1833 became a lieutenant in the 62nd Regiment, he resigned in 1834 after serving in India. Shortly after Day went to Sydney where he worked as a clerk to the Executive Council, and served in the office of the colonial secretary in 1835. By January 1836 he was appointed police magistrate at the Vale of Clwydd, and at Maitland and Muswellbrook in 1837.
In 1838, Day was responsible for the arrest of eleven men who had killed at least twenty-eight Aborigines at Myall Creek on the Liverpool Plains. This event is known today as the Myall Creek massacre. (Source: Australian Dictionary of Biography website)