Xerxes is a dark gray horse belonging to horse wrangler Harlan Grayson. Grayson rode Xerxes in the Tarrell Overland Horse Race when the race came to Miradero. Xerxes finished the race second, but Grayson was declared the winner of the race when the first-place finishers, Lucky and Spirit, were disqualified. Before she realized Lucky was in the race, Aunt Cora thought Xerxes had good chances of winning.
Grayson used Xerxes to haul a cart with barrels of water from Grayson's land, where the river had been dammed up by a landslide, back into Miradero to sell water to the townspeople at $5 a bucket.
Xerxes was a great king of Persia in the 6th and 5th centuries BC.