In Homeric Greek, “hero” (ἥρως, hḗrōs) refers to a man who fought (on either side) during the Trojan War. By the historical period, however, the word came to mean specifically a dead man, venerated and propitiated at his tomb or at a designated shrine, because his fame during life or his unusual manner of death gave him power to support and protect the living.
the earliest written reference to hero-cult is attributed to Dracon, the Athenian lawgiver of the late seventh century BC, who prescribed that gods and local heroes should both be honoured according to ancestral custom. The custom, then, was already established, and there were multiple local heroes. The written sources emphasise the importance of heroes’ tombs and the temenos or sanctuary, where chthonic rites appeased their spirits and induced them to continue to favour the people who looked to them as founders, of whom founding myths were related.
Source: Greek hero cult – Wikipedia