Eostra is the leader of the Soul Eaters and the Eagle Owl Mage.
Thiazzi, the Oak Mage, is killed in Oath Breaker.
Sheshru, the Viper Mage, is killed in Outcast and is Renn's mother.
Nef is the Bat Mage. When she lost her son, she almost killed herself with grief but Torak's Fa kept her from committing suicide. In Soul Eater, she sacrificed herself to quench the light of one of the shards of the Fire Opal.
Tenris was the Seal Mage. He died in Spirit Walker.
Torak's Fa, the Wolf Mage, was a Soul Eater but once they became evil he did all he could to stop them. He died in Wolf Brother.
The seventh Soul Eater is the Walker.