Joseph Ignatz Sadler (February 17, 1725 - January 9, 1767) was a Czech painter.
Sadler was born in Olomouc, and primarily painted religious-themed frescoes. acting especially in Moravia, for example the frescoes on the ceiling of the church of the Most Holy Trinity Church, Fulnek. He was the brother-in-law of the painter Johann Christoph Handke. He was of German minority ethnics in Moravia.