Zachary Hillander is the High King of the Sacor Clans. The younger brother of Prince Amilton, he was to govern Hillander Province, the southernmost of the twelve provinces, while Amilton reigned. Their father, King Amigast, changed the order of succession when he finally realized how cruel and his elder son was, and that he was incapable of leadership. Though Zachary had protested, he was eventually crowned king.
Amilton's attempt at a coup was the climax of Green Rider.
King Zachary has had a life long love of dogs, and is rarely seen without his faithful Hillander Terriers. Since he was a young child he has been friends with Laren Mapstone, whom he called his "big sister". Now, as captain of the Green Riders, she is still one of his closest friends and most trusted confidants. Laren's nickname for him is "Moonling."
He falls in love with Karigan after she fervently tells him he needs to look at how he runs his kingdom. Karigan later falls for him, but their love cannot be reciprocated as she is a commoner. Zachary eventually is betrothed Lady Estora (Karigan's friend and late F'ryan Coblebay's former lover) for the political advantage of the Coutre Province alliance. He was eventually married to Lady Estora on his deathbed after being shot by a father whose son was found guilty of treason against the King.
King Zachary, during the ball room dance event, encountered a person who wore the mirror mask and foresaw rains of arrows.