Karl Leisner was a German Catholic priest and resistance fighter who was held in the Dachau concentration camp during the Nazi regime. Born in Rees in 1915, he was a dedicated youth leader and deacon before his arrest for criticizing Adolf Hitler. While imprisoned, he suffered from tuberculosis, a condition worsened by the harsh camp environment. Despite his failing health, he was secretly ordained as a priest by a fellow prisoner in 1944. He passed away in 1945 shortly after the liberation of the camp.