O'Grady was inspired by Sylvester O'Halloran and played a formative role in the Celtic Revival, publishing the tales of Irish mythology, as the History of Ireland: Heroic Period (1878), arguing that the Gaelic tradition had rival only from the tales of Homeric Greece.
O'Grady was a paradox for his times, proud of his Gaelic heritage, he was also a member of the Church of Ireland, a champion of aristocratic virtues (particularly decrying bourgeois values and the uprooting cosmopolitanism of modernity) and at one point advocated a revitalised Irish people taking over the British Empire and renaming it the Anglo-Irish Empire.
O'Grady's influence crossed the divide of the Anglo-Irish and Irish-Ireland traditions in literature.
His influence was explicitly stated by the Abbey Theatre set with Lady Gregory, W.
B.
Yeats and George William Russell attributing their interest in the Fenian Cycle of Gaelic tradition in part to him.