The Gigantes or giants were a class of extremely large and often monstrous men who were closely related to the gods. According to Hesiod's Theogony, first Giants were born from the spilt blood of Uranus which fell on earth, when Cronus and his brothers castrated him.
Agrius - a man-eating Thracian giant who was half-man and half-bear. He was transformed into a bird by the gods, along with his companion Oreius as punishment for their cannibalism.
Alcyoneus - the eldest of the Thracian giants. He led the rebellion against the Olympian gods and was said to be immortal in his homeland Pallene. He was later slain by Heracles who came to aid the Olympians.
Aloadae - twins who attempted to storm Olympus and later imprisoned Ares in a bronze jar, when the god of war went to confront them.
Alpos - a Sicilian giant who terrorised the nearby area. He had many arms and head covered with vipers. He was slain by Dionysus
Antaeus - a Libyan giant who challenged all by-passers to a wrestling match. He killed them and collected the skulls because he wanted to build a temple out of them to honor his father Poseidon. He was slain by Heracles in a wrestling match.
Argus Panoptes (Argos) - a hundred-eyed giant, tasked by Hera to guard Io from Zeus. Argos never closed all of his eyes, only a few needed to sleep at the same time. Zeus sent his messenger Hermes to slay the giant and free Io.
Chrysaor - a son of Poseidon and Medusa, sometimes said to be a giant while on other accounts is described as a winged boar.
Cyclopes (Younger) - a tribe of one-eyed cannibalistic giants who shepherded flocks of sheep on the island of Sicily. One of them was Polyphemus who captured Odysseus and his men, but was later blinded and tricked by the hero.
Enceladus - one of the Thracian giants who was fighting against the Olympians. He was struck by the spear of Athena and was buried underneath Mount Etna.
Gegenees - earth-born tribe of six-armed giants, fought by Jason and the Argonauts on Bear Mountain in Mysia. It was one of their encounters on the way to Colchis.
Geryon - a three-bodied, four-winged giant who dwelt on the red island of Erytheia. He was encountered and defeated by Heracles in his tenth labour.
Laestrygonians - a tribe of man-eating giants, encountered by Odysseus and his men. They destroyed all but one ship, by throwing rocks of the cliffs when Odysseus and his men were trying to escape.
Polybotes - a giant who fought Poseidon during the Gigantomachy. He was defeated by the god, when Poseidon ripped off a part of island Kos with his trident and hurled it at him.
Porphyrion - a giant who started a war against Olympians. He was said to be the king of the giants and wanted to rape Hera during the war but was prevented by Zeus who had struck him with thunderbolt. He was later killed by Heracles.
Typhoeus (Typhon) - a monstrous immortal storm-giant of enormous size, sent by Gaea to kill Zeus as retribution for imprisoning her children in Tartarus. Typhoeus was defeated by Zeus and, like the titans, imprisoned in the pit of Tartarus
The Elder Cyclopes and Hekatoncheries were born even before the first giants. They came from the union of Gaea(the earth) and Uranus(the heavens) who also gave birth to the Titans. In general, elder Cyclopes and Hekatoncheries, although being also a race of giants, are often acknowledged apart from the rest of the giants because of their ancient knowledge and powers.
Cyclopes (Elder) - three one-eyed giants who forged Zeus' thunderbolt, Hades' cap of invisibility and Poseidon's storm-raising trident. Their names were Arges, Brontes and Steropes.
Hekatoncheires - three one-hundred-handed giant gods of violent storms and hurricanes. Their names were Briareus or Aigaion(The Vigorous), Cottus(The Furious) and Gyges(The Big-Limbed).