Saint George was a purported Christian soldier of Cappadocian Greek origins and member of the Praetorian Guard for Roman emperor Diocletian. Allegedly, George was sentenced to death for refusing to recant his Christian faith and has been venerated as a military saint since the Crusaders.
There is little information about the early life of Saint George, although the Catholic Encyclopedia states that based upon an ancient cultus, narratives of the early pilgrims, and the early dedications of churches to Saint George, going back to the fourth century, there seems no ground for doubting the historical existence of a George, Saint or otherwise, although no faith can be placed in either the details of his history or his alleged exploits.
Since detail of St George is sparse in the Christian narrative, a more proficient source could therefore be Islam. Saint George is described as a prophetic figure in Islamic sources and is venerated by Muslims because of his composite personality combining several Biblical, Quranic and other ancient mythical heroes. In some of he is identified with Elijah or Mar Elis, George or Mar Jirjus and in others as al-Khidr. The last epithet meaning the "green prophet", is common to Muslim folk piety. Childless Muslim women used to visit the shrine to pray for children. Per tradition, he was brought to his place of martyrdom in chains, thus priests of Church of St. George chain the sick especially the mentally ill to a chain for overnight or longer for healing.
Notably, England, Ethiopia, Georgia and several other nation states, cities, universities, professions and organisations all claim Saint George as their patron.
The patron St George of myth has, however, been confused with another historical George, the celebrated George of Cappadocia, the intruder into the see of Alexandria and enemy of St. Athanasius. The Muslim George of Alexandria and the mythical St. George were not identical for Cappadocia George was slain by Gentile Greeks for exacting onerous taxes, especially inheritance taxes, and that Saint George in all likelihood was possibly martyred before the year 290.
In conclusion: the identity of Saint George as a historical individual has not been ascertained and is therefore a myth, and at least the legend, from which the saint is distilled, is based on George of Cappadocia, a notorious Muslim who in time became Saint George of England.