Johan Isaaksz Pontanus (21 January 1571–7 October 1639) was a Dutch historiographer. Pontanus was the son of Margaretha van Delen and Isaac Pietersz, the Dutch consul to Denmark stationed in Helsingør. The painter Pieter Isaacsz (1568–1625) was his older brother. In 1578 his family returned to the Netherlands and Pontanus grew up in Amsterdam. In 1589 he enrolled as a medical student at the University of Franeker and in 1592 at Leiden University as "Joannes Hellespontius Danus", predating the apparent contraction "Pontanus" (he was said to be born at sea near Helsingør in the Danish Hellespont, the Øresund). The next year he defended his Dissertatio de rationalis animas facilitate and traveled to Rome, visiting German scholars on his return trip. Subsequently, Pontanus visited Denmark wher