Hieronymus Megiser (c. 1554 in Stuttgart – 1618 or 1619 in Linz, Austria) was a German polymath, linguist and historian.
From 1571 he studied at the University of Tübingen, and was a favourite student of the humanist and philologist Nicodemus Frischlin.
From 1582 he studied jurisprudence in Padua and was then active as a private tutor of young noblemen from Croatia and Styria.
After further travels he settled in Frankfurt am Main and married the daughter of the printer Johann Spiess.
In 1612 he published Annales Carinthiae or Chronica des Loeblichen Ertzhertzogthumbs Khaerndten, which he signed as his own work, although it was mainly written by Carinthian pastor Michael Gothard Christalnick and only edited by Megiser on the request of the Carinthian Estates.