Barcode number 330417291559. The kid who told the group to split up in 2009. Max didn't think it was a good idea, but at least a few kids survived. Max and Zack crossed paths several times during the series, with Zack still behaving like a strategist. In several episodes, he acted brashly and without compassion for Max, but in the end, he always did the right thing.

He shot himself in "And Jesus Brought A Casserole" to save Max's life. His organs were redistributed, and he was still "alive" in "Designate This." Max discovered him several months later, except he now had implants and memory alterations. Brainwashed my Manticore to believe that Logan/Eyes Only was out to harm the X-5's, Zack decided to kill Logan. Lending to this decision was Zack's loove for Max. After having to fight with Zack, and accidentally causing an electrical short that disabled his memories of her, Max made the painful decision to have Logan set Zack up with a new life, free of the memories of Manticore ("Some Assembly Required").