Avrana Kern: Avrana Kern leads the Second Brin Exaltation Project and survives the destruction of its station as an uploaded personality in the Sentry Habitat. She guards the planet where her experiment continues and later advises the society formed by humans and spiders.
Bianca (the alchemist): A scholar of Great Nest who works in a silk laboratory inside an ant nest. Her plan turns a marching ant colony into allies.
Brenjit Nessel: A colonist aboard the Gilgamesh who joins Scoles's mutiny rather than go to the moon base. She reaches the green planet in a stolen shuttle and runs into the forest when Karst's security team starts shooting the survivors.
Fabian: A small male spider of Great Nest who invents a chemical architecture for ant colonies, uses it to destroy an army, and makes his help conditional on the killing of a male becoming a crime.
Holsten Mason: Holsten Mason is a classicist and member of the Gilgamesh's Key Crew. He translates Old Empire signals and recognizes the spiders' transmissions as language.
Isa Lain: Isa Lain is the chief engineer of the ark ship Gilgamesh. She works to keep the ship and its human cargo alive across a journey of millennia.
Karst: Karst leads the security detail aboard the Gilgamesh. His first name is not given.
Portia (the envoy): A large spider from the Great Nest who travels north to investigate the ants and their colony. She steals a crystal from the colony, then escapes by gliding away.
Portia (the first Portia): A jumping spider eight millimetres long who hunts with a patience that looks almost like thought, and whose children are said to inherit the world.
Renas Vitas: Renas Vitas is the science chief aboard the ark ship Gilgamesh. She argues that the crew must attack rather than risk trusting an offer of peace from Kern's World.
Scoles: Scoles leads the mutineers aboard the Gilgamesh and takes Holsten Mason and Isa Lain hostage. He gets a shuttle to the green planet, where Karst's security team shoots him.
Sering: Sering is the volunteer chosen to ride the Brin 2 Sentry Pod in cold sleep and mentor uplifted primates. He sabotages the station, but Kern escapes in the pod.
Viola (the speaker of Seven Trees): A powerful female of Seven Trees who is nominally in control of its force at Great Nest and later leads the Sky Nest mission toward the edge of the sky.
Vrie Guyen: Vrie Guyen commands the ark ship Gilgamesh and steers it to Kern's World. He plans to return and take the planet, then tries to copy his mind into the ship's computer.