Herodius was the name of a high priest of the church of the Triune during the time of the Sin War novels. The other two high priests at the time were Malic, high priest of Mefis, and Balthazar. It is never explicitly stated whether he was the high priest of Bala or Dialon, but seeing as Balthazar probably was the high priest of Bala due to his name, it is reasonably to conclude that Herodius was the high priest of Dialon.
Both he and Balthazar are only mentioned by name once in the books, and play no part in the plot at all.
- Birthright, page 156. Richard A. Knaak, 2006.