Kilian Caspar Flasch (July 16, 1831 – August 3, 1891) was a German-born prelate of the Roman Catholic Church who served as bishop of the Diocese of La Crosse in Wisconsin from 1881 until his death in 1891.

[4] Flasch entered the College of Notre Dame in South Bend, Indiana, and continued his studies at St. Vincent Seminary in Latrobe, Pennsylvania.

[3] He remained at the seminary until the spring of 1865, when he became a chaplain and instructor at a convent of the Franciscan Sisters of Perpetual Adoration in Jefferson, Wisconsin due to ill health.

[1] Flasch briefly resumed his duties at the seminary before being named pastor of St. Mary's Visitation Parish in Elm Grove, Wisconsin in May 1867.

[1] He returned to St. Francis Seminary in November 1874, where he resumed his post as professor of moral theology in addition to becoming spiritual director.

[2] The trip proved unsuccessful and Kilian Flasch returned to La Crosse, where he died on August 3, 1891, at age 60.