Ireland's Immortals tells the story of one of the world's great mythologies. The first account of the gods of Irish myth to take in the whole sweep of Irish literature in both the nation's languages, the book describes how Ireland's pagan divinities were transformed into literary characters in the medieval Christian era--and how they were recast again during the Celtic Revival of the late nineteenth and early twentieth centuries. We meet the heroic Lug; the Morrígan, crow goddess of battle; the fire goddess Brigit, who moonlights as a Christian saint; the mist-cloaked sea god Manannán mac Lir; and the ageless fairies who inspired J.R.R. Tolkien's immortal elves. Medieval clerics speculated that the Irish divinities might be devils, angels, or enchanters. W. B. Yeats invoked them to reimagine the national condition, while his friend George Russell beheld them in visions and understood them to be local versions of Hindu deities. The book also tells how the Scots repackaged Ireland's divine beings as the gods of the Gael on both sides of the sea--and how Irish mythology continues to influence popular culture far beyond Ireland.