Alright, it's been a day. I guess the questions were a bit difficult now that I think about it.

Jack and Sylvia are the two vampire bosses from Illusion of Gaia. They guard the third mystic statue in the sunken ruins of Mu.

The evil Demon King from Actraiser that was defeated in the first, only to be revived by the 13 Demons of Sin in Actraiser 2 is Tanzra.

I guess it's time for someone else to go.