Amaltheia is a sacred goat and the surrogate of Zeus.
When Rhea hid Zeus from Kronos, she ordered Amaltheia to nurse and care for Zeus. After the Titan war, Zeus sacrificed her and used her hide to create Aegis, though she was eventually brought back to life.
The Diary of Luke Castellan
When Thalia Grace was twelve, she ran away from home in Los Angeles and discovered Amaltheia. She followed her, seeing the goat as a sign from Zeus. She was lured to a dragon's cave where she met Luke Castellan. Later, Amaltheia would reappear in Richmond, Virginia, where she would lead Thalia and Luke to Halcyon Green's mansion which held a treasure for Thalia, and which also turned out to be a deadly trap. But with the help of Luke, Thalia discovered Amaltheia had led her to a gift from Zeus, Aegis, which she was able to use to battle the Leucrotae and save Luke.
- Her udders are labelled with Greek letters.
- Her teats read: Nectar, Milk, Water, Pepsi, Press Here for Ice, and Diet Mountain Dew. According to Percy Jackson's Greek Gods, Amaltheia can also produce magical goat milk in many different flavors, including Low Fat, Chocolate, and Baby Formula.
- In traditional Greek mythology, when Zeus reached maturity, he created his thunder-shield (Aegis) from her hide and the horn of plenty from her crown.
- Analtheia, a moon of Jupiter, is named after her.