Cornelius Loos, also known as Losaeus Callidius (1546 - February 3, 1595), was a Roman Catholic priest, theologian, and Professor of Theology, and was the first Catholic official to write publicly against the witch trials then raging throughout Europe. For this, he was imprisoned and forced under torture to recant; his work was confiscated and suppressed by Church officials, and the manuscript was lost for almost 300 years.