Known as Hecatonchires, they were giant beings from Greek myth. Having one hundred hands and fifty heads, their father Ouranos found them disgusting and threw them into Tartarus. This act upset Gaia greatly, causing her great pain and setting in motion the overthrow of Ouranos by Cronus, who continued their imprisonment in Tartarus.
The Hekatonkheires remained there, guarded by the dragon Campe, until Zeus rescued them, advised by Gaia that they would serve as good allies against Cronus and the Titans. During the War of the Titans, the Hekatonkheires threw rocks as big as mountains, one hundred at a time, at the Titans, overwhelming them.
After the War of the Titans, the Hekatonkheires became the guards of Tartarus. Briareos became the son-in-law of Poseidon, who gave him "Kymopoliea his daughter to wed."