Doctor Zakos is a Mogadorian scientist and replacement of Doctor Lockam Anu, who was executed for the apparant failure of his memory transfer technology. He works at Ashwood Estates and has his own laboratory where the bodies of One, many human Greeters and Malcolm Goode, the only one who survived, are held captive for experiments and interrogation.
Zakos uses Anu's research as a basis to improve and develop the memory extraction technology so that the Mogadorians can learn more about the Garde. He reveals to Adamus, the original subject of the experiment, that the new improved version would only work with the original test subject and that he has Number One's body perfectly reserved.
Adam, desperate for a way to save Number One's consciousness in his mind, manipulates his father Andrakkus Sutekh to allow Zakos to do the experiment. When this experiment doesn't work, Zakos is furious but acknowledges that he could extract all of One's memories onto a disc but for it to work Adamus would have to die. He also reveals that he has Malcolm Goode stored in his lab.
Upon learning that Adam betrayed the Mogadorians, Zakos volunteers him for the new experiement that would kill him and the General agrees. In the lab, Adamus notices a syringe of anesthetic and stabs it into Zakos' neck, knocking him out, before freeing Malcolm and wiring himself up to the machine in order to save One. When the Earthquake Generation Legacy is given to Adamus he destroys Ashwood Estates.
In Last Defense, Agent Noto reveals to Malcolm that Zakos survived by showing him a recording of Zakos from after Adam destroyed the tunnels. Hearing the recording filled Malcolm with fear and disgust.
In Hunt for the Garde, Doctor Zakos calls Phiri Dun-Ra, who is on the Anubis. Phiri reveals that he has a large scar across his domed skull, which he received when Adam destroyed Ashwood's tunnels. Phiri also reveals that he was a regular visitor to Setrákus Ra in the Mogadorian Mountain Base, and oversaw most of the experiments there. Once a massive Piken broke loose, and half of Phiri Dun-Ra's men were killed. Zakos shrugged it off, and assigned Phiri new men, which were responsible for the escape of Number Nine a week later (Infiltration of West Virginia).