Ioannis Theofanidis () was a Greek Navy officer and scholar.
After studies in the Hellenic Navy Academy, Theofanidis served during the Greco-Turkish War of 1897 and the Balkan Wars (where he was adjutant to the Greek fleet commander, Pavlos Kountouriotis), finally retiring as a Rear Admiral in 1923.
Theofanidis was a hero during the evacuation of Smyrna in 1922, working with Asa K. Jennings and Admiral Halsey Powell, saving hundreds-of-thousands of lives.
Having taught history in the Navy Academy, Theofanidis dedicated himself to historical research thereafter, editing publishing the archives of his wife's great-great-grandfather, the hero of the Greek Revolution Theodoros Kolokotronis, studies on the history of the Greek Navy in the periods 1824âÂÂ26 (àÃÂóÃÂý ÃÂֈÃÂýõþñÃÂÃÂ÷ÃÂïñÃÂ, ÃÂÃÂÃÂÿÃÂïñ ÃÂÿàõûû÷ýùúÿàýñàÃÂùúÿÃÂ. ãõÃÂÃÂÃÂüòÃÂùÿà1824 - ÃÂÃÂÃÂïûùÿà1826: ÃÂõÃÂúñÃÂÃÂÃÂÿý-ÃÂñÃÂ÷ÃÂõÃÂÃÂ-ÃÂûõþìýôÃÂõùñ-ÃÂõÃÂÿûÃÂóóùÿý, 1932) and 1909âÂÂ13 (ÃÂÃÂÃÂÿÃÂïñ ÃÂÿàÃÂûû÷ýùúÿàÃÂñàÃÂùúÿà1909-1913: üõÃÂ'õùúÃÂýÃÂý úñù ÃÂñÃÂÃÂÃÂý, 1923), on the downfall of Napoleon after the Battle of Waterloo (ààÃÂÃÂÃÂùàÃÂÿàÃÂñÃÂÿûÃÂÿýÃÂÿÃÂ: ÷ óñûûùúî ÃÂÿàûî üõÃÂì ÃÂÿ ÃÂñÃÂõÃÂûÃÂ-"ÃÂõûõÃÂõÃÂÃÂýÃÂ÷ÃÂ"-"ÃÂÿÃÂøÿÃÂüÃÂõÃÂûñýÃÂ"-ÃÂóïñ ÃÂûÃÂý÷, 1933) and on his campaign in Syria against Sir Sidney Smith (ÃÂñÃÂÿûÃÂÃÂý - ãõàãïôýõàãüùø, 1929).
In the 1920s he came across and became obsessed with the study of the Antikythera mechanism, selling off family property to finance his research into reconstructing a model of the device. He published a first set of his findings in 1934, but most of his work remained unpublished and unknown after his death.
With his wife, Aikaterini Ioannidou, he had two children, a daughter Elli and a son, Iason, who also became a naval officer.