Zack's signature appearance is a tall, well-built man with spiky black hair and the iconic sky blue "mako eyes" common to SOLDIER members. In his most iconic appearance as a SOLDIER First Class, he dresses in black uniform, wearing gloves and boots, and wields the Buster Sword. He also has an X-shaped scar on his cheek, a silver stud earring in his left ear, and a single lock of hair hanging down in front of his face. Zack is upbeat, optimistic, kind, and driven, beaming with enthusiasm and energy, even under dire circumstances. His energetic nature is coupled with a short attention span and restlessness, which earned him the moniker "Zack, the Puppy" when his mentor spoke of him to others. Zack is extremely affable, befriending people quickly with ease and gaining the trust of allies. He is similarly flirty and charming with women. Over time, the dire circumstances that Zack faced did not make him bitter or pessimistic, but rather matured him away from his more restless behavior, maintaining his positive and hopeful attitude, even in his latter days. Zack's core motivation is to become a hero and protect his honor, his guiding principle. When fighting in Wutai, he affirms loyalty to comrades while equivocating as to which side is right, but spares the captain's life rather than act out of cruelty. When he eventually clashes with former comrades, he does so reluctantly, after trying each time to save them. His quest to see good in people and to support them allows him to inspire, but sometimes lead to naivete. Zack's drive is a direct contrast to Genesis, who seeks heroism for the glory, validation, and superiority coming with it, where Zack seeks to surpass only himself. Though he grew cynical of his own past ambivalence as to what he was fighting for, his commitment to honor and heroism stuck with him to the end. He is especially protective of civilians and those he cares about.