Percy Jackson and the Olympians: Legends

Tartarus is monstrous in his physical form, standing at immense height, with his purple glistening flesh rippling with muscle. His fingers are tipped with razor-sharp black talons. However, his most terrifying and distinguishing feature is his face- in place of a normal face is a swirling whirlpool and inward spiral of darkness, and his voice sounds like it is being drawn back inward rather than projecting outward. Tartarus' black Stygian iron boots are each the size of a coffin, and his hands are "as large as crane scoops." His breastplate has faces of gorgons, monsters, cyclopes and drakons all pressing against his armor as if trying to escape. According to Percy, Tartarus is so massive, and radiates such pure malevolence, that Percy wanted to crawl away and hide as soon as he saw him, and even dropped his sword in terror. Tartarus' laughter sounds like a mountain "cracking in half". According to Annabeth, everything around Tartarus seems to be drawn to him.

Literally being the abyss where monsters go to regenerate, Tartarus is, fittingly, a completely evil and sadistic being whose whole existence is to bring sorrow and death. He showed himself to be a highly arrogant god with an immense disdain and contempt for humans and even the titans, whom he openly described as "lesser beings" after easily destroying them. However, Tartarus is honest and admits when someone forces him to take direct action. Like other primordials, Tartarus hates assuming a physical form, since that prevents him from being everywhere in his domains; however, he claimed to have a taste for having a physical form and also showed delight in inciting terror in his victims, showing himself to be a massive sadist. However, like some of his siblings, he also proved to be generally an impartial entity, to the point of being completely devoid of feelings and ideals.

Tartarus is the father of Typhon and the Gigantes, of whom Gaia is the mother. The father of Tartarus is Chaos. He is the "prison guard" of Tartarus, the darkest pit in the Underworld where monsters go to reform once they are slain. Tartarus is also the place where Uranus threw, in chains, the Elder Cyclopes and the Hekatonkhieres, and the place where most of the Titans were chained after the First Titan War, thus literally making Tartarus both a place and a being. He is one of the Protogenoi.