Origin
Not to be confused with the Titans, the Giants were born together with the Furies from Gaia, the Earth and Ouranos when he was castrated.
Description
The Giants were as tall as mountains and so strong as to be unbeatable. According to Apollodorus, their shaggy hair drooped from their heads and chins, and they had dragon scales on their feet. The mightiest Giants were Porphyrion and Alkyoneus. Alkyoneus could remain immortal as long as he fought in the land of his birth, Pallene, in the region of Thrace. A bold troublemaker, Alkyoneus dared to steal some cows owned by the Sun.
Stories The Giants tossed house-sized boulders and burning oak trees at Mount Olympus to pass the time. The Gods were slow to react, as they feared the giant’s reaction. Zeus had received an oracle, or prediction of the future. This oracle declared that the gods could kill the Giants only if they had the help of a mortal. This mortal was Hercules. The Earth, who was the mother of the Giants, learned this too, and she tried to prevent Hercules from going to help the gods. But Zeus had a plan. First he forbade the Sun from shining, then the Moon and the Dawn. Before anyone knew what was happening, he sent Athena with her chariot to bring Hercules up to Mount Olympus.
After another quarrel between Gods and Giants, the war was declared and soon the mighty Giants were climbing up Mount Olympus led by Alkyoneus. Hercules came to the cliff where he could see the monstrous Giants approaching. He drew his bow and shot Alkyoneus with an arrow that sank completely into the giant's shoulder. The giant lost his grip and fell to the ground unconscious, with an enormous crash.
Soon Alkyoneus began to revive. But before he woke up completely, Athena told Hercules that Alkyoneus would not die unless he was outside of his birthplace, in Thrace. So Hercules dragged Alkyoneus far away, and there he died.
Meanwhile, Porphyrion had reached the top of Olympus. He had Hera cornered between the rocks and the sheer cliff. When Porphyrion began to attack the goddess, Hera called for help. Zeus cast his thunderbolt at Porphyrion, leaving him dazed, and Hercules, who had just rejoined the battle, shot him dead with an arrow.
Now all the gods and Giants entered the fight. Apollo shot one of the Giants in the right eye, and Hercules shot him in the left eye. Dionysos killed one by whacking him with his thyrsus, or staff. Hecate set another Giant on fire with torches. Hephaistos eliminated one by pelting him with white-hot metal.
Two of the Giants turned to flee. Athena caught the first one and imprisoned him under the island of Sicily; Poseidon broke off a piece of the island of Cos and threw it at the other. Hermes wore Hades' helmet and slew a Giant as he ran away, and Artemis killed another. Even the Fates killed a couple of Giants, fighting with clubs made of bronze. Finally it was all over. Zeus had struck down the rest of the Giants with his thunderbolts, and Hercules finished them off where they lay.
From Monstrous.com