Essun
The trilogy's protagonist, an orogene who has lived as Damaya, Syenite, and Essun, and whose right arm petrified when she opened the Obelisk Gate at Castrima. She leads the comm's survivors to Rennanis, crosses through the planet to find her daughter, and sacrifices herself in their final standoff, turning almost wholly to stone before Hoa rebuilds her as a stone eater.
Nassun
Essun's young daughter, a powerful orogene convinced that a world so cruel has no right to continue. She journeys with Schaffa to Corepoint meaning to pull the Moon down, but her mother's tearful sacrifice finally shows her she is loved, and at the last moment she catches the Moon instead, ending the Seasons at the cost of her own hand.
Hoa
The ancient stone eater who tells Essun her own story, originally a tuner of Syl Anagist named Houwha. Forty thousand years ago he redirected the Plutonic Engine's power into the Moon and hurled it from orbit; in the present he protects Essun, ferries her party through the planet, and finally remakes her stone body into a stone eater so she can remember who she was.
Schaffa
The Guardian who broke Essun's hand when she was a girl but has become, in effect, Nassun's true father, shepherding her across the world despite the ceaseless torment of his corestone. His mind gives way during the passage through the planet's core, and after a machine at Warrant strips the corestone out, he dies free of pain and at peace.
Steel
The gray stone eater who has fastened himself to Nassun, steering her toward ending the world; when she considers transforming Schaffa, his account of immortality's unbearable loneliness, drawn from his own forty thousand years, dissuades her. The coda reveals he is Remwha, another of Hoa's fellow tuners.
Father Earth
The living, conscious planet, which has hated humanity since the theft of its Moon and made the Fifth Seasons its long punishment. It struck first on Launch Day, seized twenty-seven obelisks, and made the tuners the first stone eaters; in the end it accepts a bargain returning its Moon and dismantling the obelisks in exchange for ending the Seasons.
Kelenli
A woman of Syl Anagist who can pass as a full citizen but shares the tuners' nature, and the last lorist of the murdered Niess people. She teaches the tuners the buried truth of their origin, and Hoa's love for her, pregnant on Launch Day, drives his split-second choice to redirect the Engine's power into the Moon.
Alabaster
Essun's mentor, the orogene who split the continent to start the Season and completed his own petrification before this book begins; Antimony remade him as a stone eater. The journal he left at Corepoint, recording his grief and his experiments with the Gate, hands Nassun the spare key of twenty-seven lesser obelisks.
Ykka
Castrima's orogene leader, at first enraged that Essun's defense of the comm ruined the geode where they lived, later her partner in guiding the survivors to Rennanis. Essun makes a point of showing her the lobotomized node maintainer so the comm's new home is built with its worst sin in plain sight.
Lerna
Castrima's healer and Essun's longtime friend, who becomes her lover on the desert crossing; he later tells her she is pregnant and pleads with her to abandon a mission sure to finish her petrification. He insists on coming to Corepoint anyway and is killed when rival stone eaters attack during the transit.
Tonkee
Essun's friend, who pushes her to examine whether she wants to rescue Nassun or simply be near her again, noting the girl has managed alone for more than a year. She travels with Essun all the way through the Earth to Corepoint.
Gallat
The conductor who heads the Plutonic Engine project in Syl Anagist, raised in the same household as Kelenli and her lover. He is so certain the tuners are mere tools that he cannot grasp why revealing the briar patch, where the Niess are drained as living batteries, is monstrous.
Danel
A former general of the Rennanis army, once of the lorist caste, who asks to accompany Essun so that someone can witness what happens and set it down. Danel joins the party Hoa carries through the Earth toward Corepoint.