The librarian of Sarpeidon who sends the planet's people into their past by the atavachron before their sun goes nova.
Mr. Atoz is the librarian on Sarpeidon, whose star Beta Niobe is about to go nova. In All Our Yesterdays he oversees the atavachron, a machine that sends the planet's people into chosen periods of its history, preparing them so they can survive there.
When Kirk, Spock and McCoy arrive, Atoz assumes they are local stragglers and sends them into the past. Once they find their way back to the library, Atoz himself leaves for his chosen era just before the star explodes. He was played by Ian Wolfe.