Hyperion

Hyperion (also known as "Titan god of light", "Father of Helios", and "Lord of the East") is one of the twelve Titans of Ancient Greece, which were later supplanted by the Olympians. He was the son of Gaea and Uranus, and was referred to in early mythological writings as Helios Hyperion, 'Sun High-one'. His symbols are an open eye, his name means ' watcher from above ', and a blazing sun. He is best known for helping Kronos murder their father Uranus and fighting against the gods in the first great war.

Apperance
Hyperion is decribed by Percy to be tall and strong with golden armor and eyes like mini suns. He is also stated to be the strongest of the East,West,North, and South. Although he is immortal and capable of changing to any size, he never does so in the book, and is described by Percy as one of the hardest villans he's ever fought.

The Series
Hyperion was first shown in a dream on Mount Tamalpais talking to Krios about Prometheus and the trap for the heroes. He also mocked Atlas who was complaining he wanted to fight. Hyperion was the only other titan besides Kronos shown fighting in the battle of Manhattan (Prometheus didn't fight). He led an army consisting of draceane demigods and laistrigonian giants into central park, where he confronted Percy, the Athena Cabin, Artemis' hunters and the nature spirits led by Grover and Leneus. He dueled Percy and was able to blind him for a moment until Percy was able to move the fight to the water. Percy with his powers made a storm long enough for hyperion to be trapped in a maple tree by the satyrs and nymphs. It is unknown if Hyperion would be able to escape from the tree when reaching full form.