Zack is a Lawndale High student in Daria's year, in the same English/Language Arts classes as her. His name comes from Mr. O'Neill's seating chart in "Cafe Disaffecto".
He's not the same guy as Zachary, one of Quinn's suitors.
Zack in Fanfic
Josh usually appears as a background character without much to say, but he was given a major expansion in the "Ethan Yeager in Lawndale" series by Shiva.