The River Styx occupies a position of dense mythological and psychological significance across the depth-psychology corpus. As the preeminent boundary between the living and the dead, it functions simultaneously as cosmological fixture, oath-substance, and initiatory threshold. The corpus reveals several distinct registers of engagement. Keréni and Hesiod treat the Styx as primordial deity — eldest daughter of Ocean and Tethys, wife of Pallas, her waters lethal to gods and mortals alike, her name etymologically bound to stygein, ‘to hate.’ Nagy’s philological analysis recovers a paradox at the Styx’s core: the very waters associated with death are simultaneously an elixir of immortality, as the Achilles-immersion tradition attests, making the Styx a locus where mortality and the aphthitos, the imperishable, collide. Liz Greene reads the crossing of the Styx through a Plutonian lens, emphasizing Charon’s toll as the enforced surrender of ego-property during psychological descent — an image of value given away at the threshold of transformation. Lattimore’s scholarly annotation to the Iliad encodes the Styx as the most binding oath available to gods, a guarantee of cosmic order. Rohde situates the river within the broader archaeology of Greek afterlife belief, noting its borrowed status in the Odyssey’s topography. Together, these voices construct the Styx not as mere scenery but as the grammar of limit, oath, and transformation within the underworld imagination.