Within the depth-psychology corpus, Ephialtes functions primarily as the philological and mythological anchor for the nightmare demon—a figure whose very name encodes the phenomenology of nocturnal oppression. Roscher’s monograph, translated and introduced by Hillman in Pan and the Nightmare, furnishes the most sustained treatment: Ephialtes (alongside the variant Epialtes) designates the crushing, leaping daemon who assails the sleeper, etymologically traceable to either iallein (‘to send,’ ‘to shoot’) or hallomai (‘to leap’), with Roscher preferring the latter as phenomenologically more precise. The figure is not merely a linguistic curiosity but a psychic reality at the intersection of fever, erotic disturbance, respiratory crisis, and mythological imagination. Critically, Roscher documents the daemon’s convergence with Typhos, with Pan, with incubi, and with Hypnos—demonstrating the nightmare’s embeddedness in a polytheistic field of overlapping daemonic agencies. In the Homeric genealogical tradition, Ephialtes also names one of the Aloadae, the giant sons of Aloeus, whose stepmother Eeriboea appears in the Iliad; this heroic-gigantomachic Ephialtes coexists uneasily with the daemonic nocturnal figure. Rohde situates Pan-as-Ephialtes within the broader economy of Greek demonology, linking nightmare to heroic cult, pollution, and the agency of daemones. The corpus thus treats Ephialtes as a nodal term: lexical, demonological, genealogical, and depth-psychological simultaneously.