Ichor is the blood of the gods. Gods rarely bled, so mortals rarely ever saw it. But occasionally a powerful monster, demigod, or even another god would attack a god and they would bleed. Some people say that Ichor was made of Ambrosia and Nectar, the food of the gods. Great demigods and heroes occasionally attacked gods and released ichor, but gods rarely did so to each other in Homeric myth.
In Ancient Crete, tradition told of Talos, a giant man of bronze portrayed with wings. When Cretan mythology was appropriated by the Greeks, they imagined him more like the Colossus of Rhodes. He possessed a single vein running with ichor that was stoppered by a nail in his back. Talos guarded Europa on Crete and threw boulders at intruders until the Argonauts came after the acquisition of the Golden Fleece and the sorceress Medea took out the nail, releasing the Ichor and killing him.