With the strike chopping "Heroes‘" sophomore season down from 24 episodes to just 11, creator Tim Kring had to improvise.

The writers had originally envisioned Season 2 as consisting of three “volumes,” or extended story arcs, but just one of those volumes, “Generations,” aired in Season 2.

A second, “Villains,” was pushed to Season 3, and a third, “Exodus,” was scrapped altogether. Also, a planned spin-off, "Heroes: Origins", never materialized due to the strike.

http://tvline.com/gallery/writers-strike-tv-2008-photos-breaking-bad-friday-night-lights-the-big-bang-theory/#!7/heroes-season-2-cast-nbc/