Joannes Gennadius (Ιωάννου Γενναδίου) was an eminent diplomat, scholar, and bibliophile.

He is also the founder of Gennadeion, or the Gennadius Library, one of the most important libraries in Greece, with over 110,000 volumes on Greek history, literature and art from Antiquity until modern times. The library is located in central Athens. In 1925, he presented this sketch of the history of education in Greece, documenting the early origins of learning in ancient times up to the early 20th century.

Gennadius, J. 1925. A Sketch of the History of the Education System in Greece. Edinburgh: Moray Place (Supplement to the Proceedings of the Edinburgh Conference of the World Federation of Education Associations.