Johann Heinrich Alsted (March 1588 – November 9, 1638), "the true parent of all the Encyclopædias", was a German-born Transylvanian Saxon Calvinist minister and academic, known for his varied interests: in Ramism and Lullism, pedagogy and encyclopedias, theology and millenarianism. His contemporaries noted that an anagram of Alstedius was sedulitas, meaning "hard work" in Latin.
Alsted was born in Mittenaar. He was educated at Herborn Academy in the state of Hesse, studying under Johannes Piscator. From 1606 he was at the University of Marburg, taught by Rudolf Goclenius, Gregorius Schönfeld and Raphaël Egli. The following year he went to Basel, where his teachers were Leonhardt Zubler for mathematics, Amandus Polanus von Polansdorf for theology, and Johann Buxtorf. From about 1608 he returned to the Herborn Academy to teach as professor of philosophy and theology.
Alsted was later in exile from the Thirty Years' War in Transylvania, where he remained for the rest of his life. In 1629 he left war-torn Germany for Weißenburg (now Alba Iulia in Romania). He was to found a Calvinist Academy: the context was that the Transylvanian royal family had just returned from Unitarianism to Calvinism. Alsted and Johannes Bisterfeld were German professors brought in improve standards. Among the students there was János Apáczai Csere. Alsted died in Alba Iulia.