A Note Regarding Spelling: I use "Zax" exclusively in this site and in my fic. The katakana (phonetic Japanese alphabet) spelling for Zax is "zakkusu", indicating an "s" or "x" on the end of his name. If his name were Zack, the katakana would be "Zakku". Offical Japanese releases spell his name "Zack's." I respect the fact that his name is translated as "Zack" in the American version of the game, but for the sake of consistency, I stick to the Japanese spelling. (On the flipside, though, I prefer Aeris to Aerith.)

And a Note Regarding Naming: "Darklighter," as Zax's last name, is purely my invention. It is in no way canon.

SPOILER WARNING!

Born in the town of Gongoga, Zax (Zacks or Zack in the American translation) was a member of the elite group of mako-infused fighters, SOLDIER. He was assigned to the Nibelheim mission along with his superior officer, Sephiroth, and two Shinra guards, one of whom was Cloud Strife.

After the madness of Sephiroth, when he was run through by his former commanding officer, Zax (along with Cloud) was taken to the Shinra mansion and subjected to Hojo's experiments. Zax was a sucessful clone of Sephiroth, but Cloud had a negative reaction to the mako and did not make a suitable host for the Jenova cells. After five years in captivity, Zax made possible Cloud's escape from Nibelheim and they traveled to Midgar together. Zax dressed Cloud in a standard SOLDIER uniform (probably one of his own). Zax had plans of returning to Midgar and possibly lying low at an old girlfriend's place (Aeris, most likely). He proposed the idea to a mostly unconsious Cloud that the two of them should become mercenaries together, an idea that lodged itself firmly in Cloud's unstable psyche. Although Zax would have had better chances leaving Cloud behind and going on his own, he stuck with him, and as a result the two were caught by Shinra forces just outside of Midgar. Zax was shot and killed while attempting to protect his companion. Left to die by the guards, Cloud's mind snapped from the trauma, and he took Zax's Buster Sword and assumed the persona of the former SOLDIER.

Zax's parents are still unaware of his fate.

Zax was probably in his late twenties at the time of his death. Had he survived, he would have likely become one of Sephiroth's clones, and forced to do his will.

Zax has his own form of resurrection in the game Ehrgeiz, in which he is a playable hidden character. His moves in the game are the same as Cloud's.