Ida of Herzfeld was a Saxon widow who lived during the late 8th and early 9th centuries. Following the death of her husband, Egbert, in 811, she dedicated herself to assisting the impoverished. She is historically noted for constructing the first stone church on the eastern side of the Lower Rhine. Her life of prayer and service to the needy led to her recognition as a saint, and she remains a significant figure in Westphalian religious history.