Styx Hades is one of the six Hades siblings, along with his brothers Acheron, Cocytus, Phlegethon and Lethe, and his only sister, Aornis. He was killed by Acheron in The Eyre Affair.

Unlike Acheron, who was pure evil, he was only mildly bad, spending much of his time reserving cars and then not turning up to view them.

Like all the siblings, he was named after one of the rivers of the Underworld.