STYX

River of Hades (4)

Solution has appeared in 2 crosswords (1 across and 1 down):

• Quick crossword No 15,836 — 2021-02-08 00:00:24
  10A: River over which Charon carried dead souls (4)
• Quick crossword No 15,612 — 2020-05-20 23:00:39
  3D: River of Hades (4)