I've always wanted to incorporate Black and White Lanters into the set but I've failed at coming up with decent picks for them so, basically, I need fictional characters that represent life and death to put as White and Black Lanterns respectively. I prefer that they don't already overlap with series that other characters in the set originate from, i.e. Star Wars, LotR, etc. It's harder than you think without going for obvious things like the Grim Reaper (who is basically Nekron anyway) and some sort of deity. Death from the Endless is tempting but doesn't work as a Black Lantern at all.
I can't promise inclusion but if you guys can come up with great choices I'll definitely try to put them in.