Ichor is the golden blood of all immortal beings. Those with Ichor, including gods, Titans, and some monsters are near-perfect beings who, in battle, can be wounded, but never permanently killed, or in the case of gods and Titans, can never be killed at all. Demigods also share their godly parent's ichor in their veins infused with their human blood, however, it cannot be seen, and it does not make them immortal.
Percy Jackson stabs the war god Ares in his ankle and makes him bleed ichor, which dissipated into the tide after Ares appeared to Annabeth Chase, Grover Underwood, and him to fight for possession of Zeus' Master Bolt.
- Alcyoneus is the only immortal who doesn't bleed ichor; instead, he bleeds oil because he was made of precious jewels by Hazel Levesque.
- Ichor in demigod's bloodstreams may let them live longer than a regular mortal, but this is yet to be seen as most demigods die early from getting killed by monsters.