Police said members of a shooting party made up of families opened fire when Christos Constantinou, 49, moved through the undergrowth.
They are thought to have been confused by the fact the victim was disguised in dark goat skins, which are used to camouflage and to mislead their prey.
The groups had fanned out in pairs of two to track down an animal for the traditional festive dinner when the accident happened.
Police in the northern Greek town of Nemea, Chalkidiki, said Mr Constantinou was pronounced dead upon arrival at hospital.
Two unidentified men, aged 25 and 28, were detained and were being questioned.