The Norse gods were divided into two groups: the war-like Aesir, who lived in Asgard; and the more peaceful Vanir, who lived in Vanaheim. The Aesir were the principle gods, and included well-known figures such as Odin and Thor.
The Norse god of the sea. Aegir was worshipped by sailors who performed human sacrifices to prevent him from sinking their ships. I can't find any confirmation of whether Aegir was an Aesir or Vanir, but as he lived in an underwater hall rather than Asgard or Vanaheim, it appears that he wasn't either.
Aegir was described as an old man, not a tentacled monster as Square depicts him. Looks like Aegir was another victim of FF3's habit of using names of more obscure mythological characters for unrelated monsters.
The god of war and head of the Aegir (the principle Norse gods). He gave one eye to drink from the well of knowledge and pinned himself to Yggdrasil, the giant ash tree that connects the nine worlds of Norse mythology, with his spear for nine days to obtain wisdom. Odin rode an eight-legged horse named Sleipnir, although in FF Odin's horse only has four legs, Sleipnir being a seperate creature.
At Ragnarok, the Norse apocalypse, Odin will be eaten by the monsterous wolf, Fenrir.
IMAGE: 12th century tapestry depicting, from left to right, Odin, Thor and Freyr
The Norse god of thunder, son of Odin and popular folk hero. He rode through the skies in a chariot pulled by two goats and caused thunderclaps with his hammer, Mjollnir.
There are a number of stories about Thor. In one of the most well-known ones, he travelled to Utgard, the land of the giants with his servent Tjalfi and the trickster Loki. There, he was beaten in a wrestling match by an old woman, was unable to lift a cat and couldn't finish a drink from a drinking-horn, while Loki lost an eating contest with a giant named Logi and Tjalfi lost a race to the giant Hugi. Before the gods left, their host revealed that the other competetors weren't all that they seemed - Logi was fire, and could consume more than any god; Hugi was thought, faster than any runner; the crone was old age, and could never be overcome; the cat was the giant serpent Jormangand, disguised with illusion and the drink contained in the horn was the sea, which could never be drained.
Aside from the fact that they both use thunder and lightning as weapons, there's very little resemblence between the Norse god and FF3's monsterous race of "Thors" - but then, a lot of the enemies to appear later on in FF3 are basically generic monsters with names of mythological creatures and characters tacked on (see angels for more examples). The most monsterous incarnation of Thor that I can find is the three-headed version linked to below.
IMAGES: 12th century tapestry depicting, from left to right, Odin, Thor and Freyr -- Depiction of a three-headed Thor from a Danish drinking horn
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ODIN

THOR

At Ragnarok, the Norse apocalypse, Thor will finally kill Jormangand but then die from its poison.
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