Josef Hafellner (1951– ) is an Austrian mycologist and lichenologist. He was awarded the Acharius Medal in 2016 for his lifetime contributions to lichenology. Before his retirement, he was a professor at the Karl-Franzens-Universität in Graz. Hafellner started developing an interest in lichens while he was a student at this institution, studying under Josef Poelt. He earned a master's degree in 1975 and a PhD in 1978, defending a doctoral thesis about the genus Karschia. In 2003, Hafellner received his habilitation. By this time, he had studied with French lichenologist (1927–2014) at Saint-Cloud, where he learned techniques of transmission electron microscopy and how their application in studying asci could be used in lichen systematics. His 1984 work Studien in Richtung einer natürliche