Ioannis G. Papadakis (c. 1820 – 1876 Greek: Ιωάννης Παπαδάκης) was a writer, mathematician, physicist, astronomer, meteorologist, and professor.

He temporarily succeeded Georgios Konstantinos Vouris until Johann Friedrich Julius Schmidt replaced him as the third director of the observatory.

He represented the island of Crete as a proxy in the Second National Assembly held in Astros Kynourias between 29 March and 18 April 1823.

Francois Arago was also affiliated with the school and Greek physicist Dimitrios Stroumpos studied at the university a decade earlier.

When Ioannis returned to Greece he was assistant to Georgios Konstantinos Vouris at the National Observatory of Athens.

The Greek revolt of 1843 was an important event because all foreign professors were expelled from the University of Athens around the same period.

He resigned his position as director of the National Observatory of Athens and moved back to Austria.

[6] Papadakis resigned in protest in 1856 when Joseph Mindler (1808–1868) a Bavarian officer of the royal court and stenographer of the Parliament was hired to teach stenography.

On 10 May 1859 a political incident rocked the university community when the students were involved in a massive protest called the skiadika (σκιαδικά).

Papadakis became dean of the Philosophical School twice and he also became president of the University of Athens right before his death in the academic year 1876–1877.

He wrote about his observations of the moons of Jupiter and published it in the Greek paper Logodos (Λογοδος).