| Johann Georg Macasius | |
| Birth Date: | 17 March 1617 |
| Birth Place: | Eger, Kingdom of Bohemia, Holy Roman Empire |
| Death Date: | 1653 |
| Death Place: | Zwickau, Holy Roman Empire |
| Fields: | Physician |
| Workplaces: | University of Jena |
| Alma Mater: | University of Jena |
| Doctoral Students: | Georg Balthasar Metzger |
Johann Georg Macasius (1617–1653) was a physician from the Holy Roman Empire. He was born in Eger, Bohemia (part of the Holy Roman Empire, now in the Czech Republic).__TOC__
He received the Medicinae Doctorate from the University of Jena in 1638 under Johannes Musaeus with a thesis entitled De natura et causis externis. In 1640, he received a second Medicinae Doctorate from the University of Jena under Balthasar Widmarcter with a thesis entitled Disputatio de inflammatione.