Sciron

Sciron (Ancient Greek: Σκίρων) is a bandit who robs travelers passing the Sceironian Rocks and forces them to wash his feet. When they kneel before him, he kicks them over the cliff into the sea, where they are eaten by a monstrous sea turtle. In the original myth, he was killed by Theseus on the way from Troezen to Athens. Sciron is a son of Poseidon.

The House of Hades
The crew of the Argo II is waylaid on the coast of Croatia by Sciron who is assisted by a giant predatory sea turtle. Hazel uses the Mist to trick Sciron to kick Hazel away from the cliff instead of off it, and then Sciron is thrown off the cliff himself and gobbled up by his own turtle. Pluto then appears to Hazel and tells her that the Doors of Death are at the lowest level of the Necromanteion, the temple of Hades near the village of Mesopotamo in the northwestern Greek region of Epirus where they are going, and will be guarded by Pasiphae, a Cretan sorceress who was the wife of Minos and mother of the Minotaur.

Trivia

 * Theseus killed Sciron in the same way as Hazel &mdash; by pushing him off the cliff.