[2] He was the son of William Sadler, an English portrait painter and engraver who came to Ireland as a boy with his father.
[3] Sadler lived at a number of different addresses before settling in Manders' Building, Ranelagh, where he died on 19 December 1839.
William Sadler III emigrated to the United States.
Sadler also taught painting and one of his pupils was James Arthur O'Connor.
Sadler was greatly influenced by Dutch genre painting and made many copies of the Old Masters.