The character Zack Fair was created late into development. He was made up along the way as Kazushige Nojima was building up the mysteries surrounding Cloud (most importantly, who he was and who he based his fake cocky personality on). Before Zack was created, Aerith was to see her first love in Cloud, though who that person would be was not yet decided until later, but there were plans to make this person Sephiroth. Eventually, Zack was placed to serve as both Aerith's first love and to solve the mysteries surrounding Cloud. When he was finally developed, Nojima asked the staff in charge of the event scenes to add foreshadowing to Cloud's true persona and to Zack himself. Zack was also the last character to be drawn by Tetsuya Nomura.
Contributed by gamemaster1991