This paper aims to compare William Faulkner’s Absalom, Absalom! and W. B. Yeats’s Purgatory from the perspective of the genealogy of the damned, the damned here being the Old South and the Protestant Ascendancy. For all their obvious differences, Faulkner’s Old South and Yeats’s Protestant Ascendancy share important features in common: the decline of aristocracy, the tendency to mythologize realities, and the sense of loss and self-loathing. In Absalom, Absalom!, Faulkner attempts to retrieve the hidden history of the South from the early years of white settlement on the Mississippi, through the Civil War and Reconstruction, to the Civil Right era. Yeats’s Purgatory dramatizes recent Irish history, looking back on the Irish independence and the establishment of the Free State as the irrevocable proof of the decline and fall of the Protestant Ascendancy. Seeing the genealogies of the Sutpen family and the Old Man as a metaphor of American South and post-independent Ireland respectively, this paper explores transnational possibilities of reading American and Irish literature against each other.