Otto Casmann (1562 – 1 August 1607)[1] (also known by the Latinized name Casmannus) was a German humanist who converted from Catholicism to Protestantism as a young man.
In 1589, Casmann joined the Schüttorf Trivial School, which in 1591 was moved to Steinfurt and expanded to the academic Gymnasium Illustre.
In 1594, Casmann obtained an appointment for the post of rector in Stade, where the City Council had set up a Gymnasium.
He began the separation of these two subjects from the Aristotelian framework of metaphysics, becoming a classical representative of the secularization of science in the early modern period.
During his time at Steinfurt he produced the work Psychologia Anthropologica, sive doctrina animae Humanae (Hanau, 1594).