Brontes the Thunderer was the name given to one of the Cyclopes, one-eyed hybrid beasts created by the Isu as part of their Olympos Project. The creature was held in a vault below the Isle of Thisvi, where it remained until its defeat and death at the hands of the Spartan misthios Kassandra during the 5th century BCE.
In Greek mythology, Brontes was one of the sons of Uranus and Gaia, and his name, "Βρόντης", meant 'thunderer'. Brontes and his brothers Steropes, Arges, and the Hekatonchires were cast into the pits of Tartaros by their father, who was repulsed by their appearance and fearful that they would usurp him. Kronos, who deposed Uranus shortly thereafter, freed them briefly before imprisoning them again. They were later freed by Zeus during the Titanomachy and forged his famed thunderbolts, along with Poseidon's trident and Hades' helm of darkness. 
Before being brought face to face with Kassandra, two other individuals claimed to have met Brontes: Barnabas, who said Brontes had taken his eye, and Empedokles, who was certain that the Cyclops was in fact Ares, the Greek god of war, and thus one of his siblings.
When Empedokles returned to the vault during the Peloponnesian War, Brontes slew him instantly. Kassandra, who had accompanied Empedokles to the vault, engaged the beast in battle and slew it, claiming the Prize of the Cyclops as well as a bludgeon in its possession.
Personality and traits
Brontes had an almost animal psychology. He was a very aggressive being, intent on destroying any moving thing in sight. His raged attacks made him capable of bringing down even the most opponent competent.
Equipment and skills
The size of Brontes was two or three times greater than that of a man, his footsteps and blows could make a place tremble, he had such a brute force that he was able to knock down a target with a single blow in a few moments. His attacks of rage made him faster and more durable being almost invincible.