For people with an understanding of Greek mythology, Tartarus is probably a name most associated with a region of the Underworld; the third region alongside the Asphodel Meadows and the Elysian Fields. In many ways though, Tartarus is more important than simply being a region of Hades, as it was also the name given to a primordial god.

Tartarus in most sources is born out of Chaos, making him sibling to Nyx (night), Gaea (earth), Erebus (darkness) and Eros (love). Tartarus was thus regarded as a great pit within the earth, as far beneath the surface of the earth as the sky was above. Hesiod would state that it would take nine days for a bronze anvil to travel the distance down.

Tartarus was firstly made use of by Ouranus (Uranus). Ouranus would imprison his own offspring within Tartarus. In went the first Cyclopes; Brontes, Steropes and Arges, and then the Hecatonchires; Briares, Cottus and Gyges. Ouranus was fearful of their power, believing that they would overthrow him. A third set of children, the Titans, though were allowed to remain at large.

Ouranus though would be overthrown by the Titans, under the leadership of Kronos. Kronos would briefly release his siblings from Tartarus, although he would soon imprison them in Tartarus again, fearful as his father had been of their power and strength.

Kronos himself would be overthrown by his own offspring, led by Zeus, in a war that would become known as the Titanomachy. Zeus would release the Cyclopes and Hecatonchires from Tartarus to aid him. When the war was won by the Olympians, Zeus would imprison those Titans who had fought against him with Tartarus.

Gradually Tartarus would become synonymous with Hades, the Underworld, and it would continue life as a prison for Zeus. Tartarus was the place in Hades where eternal punishment would be endured. In theory to be sent there required the judgement of the judges of the dead, although those who angered the gods seemed to go there directly. The likes of Ixion, Tantalus and Sisyphus were all confined there.  

As well as being a prison Tartarus was also said to have been the father of Typhon, and possibly Echidna, with Gaea. These were the most powerful of all the monsters to inhabit the world, and would become parents to many of the monsters that would challenge the heroes of ancient Greece. Typhon and Echidna themselves would challenge the power of the Olympians, and indeed came close to overpowering Zeus, although eventually Zeus would emerge successful. Zeus then confined Typhon to Tartarus as well.

Stories also told how night (Nyx) would emerge from Tartarus passing day (Hemera) as she returned.