Is Rezo Zelgadiss grandfather and great-grandfather?
No. For the longest time, due to a translation error in the anime, English-speaking fans were lead to believe that Rezo was Zelgadiss’ grandfather and great-grandfather. This is not the case, as Zelgadiss was expressing his uncertainty as to whether or not Rezo was his grandfather or great-grandfather. Kanzaka Hajime clarified in an interview that Rezo was simply Zelgadiss’ great-grandfather. You’re spelling Zelgadis’ name wrong! The official, Japanese spelling is “Zelgadiss Greywords.” You can see this on numerous pieces of merchandise as well as on his character profile at the official Slayers TV site.