Michail Hadjikonstantis (Greek Μιχαήλ Χατζηκωνσταντής) was a Greek naval officer during the Second World War.
Hadjikonstantis was born in Piraeus on November 26, 1906. He enlisted in the Hellenic Navy in 1921 and, after his studies at the naval academy, was sworn as an officer in 1926.
In 1928, Hadjikonstantis was promoted to Second Lieutenant. The following year he joined the submarine fleet. By 1934 he was promoted to Lieutenant and four years later to Lt Commander. The outbreak of the Second World War found him in command of the Submarine RHS Proteus.
On December 29, 1940, the Proteus torpedoed and sank the Italian tanker Quinto off the coast of Sasso. Italian warships then sank the Proteus with a loss of its entire crew.
On January 19, 1941, Hadjikonstantis was promoted for bravery, posthumously, to the rank of Commander.