Wikipedia
The Hekatonkheires or Hecatonchires ( stress on the third syllable; singular: "Hekatonkheir" or "Hecatonchir" ; , Hundred-Handed Ones), also called the Centimanes or Hundred-handers, were figures in an archaic stage of Greek mythology, three giants of incredible strength and ferocity that surpassed all of the Titans, whom they helped overthrow. Their name derives from the Greek (hekaton; "hundred") and (kheir; "hand"), "each of them having a hundred hands and fifty heads" ( Bibliotheca 1.1). Hesiod's Theogony (624, 639, 714, 734–35) reports that the three Hekatonkheires became the guards of the gates of Tartarus. The Hundred-Handed-Ones are "giants" of great storms, and hurricanes.
In Virgil's Aeneid (10.566–67), in which Aeneas is likened to one of them (Briareos, known here as Aegaeon), they fought on the side of the Titans rather than the Olympians; in this, Virgil was following the lost Corinthian epic Titanomachy rather than the more familiar account in Hesiod.
Other accounts make Briareos (or Aegaeon) one of the assailants of Olympus. After his defeat, he was buried under Mount Aetna (Callimachus, Hymn to Delos, 141).