Gender: Male
First Appearance: "The Journey" (mention only)
Other Appearances: None
Mr. Duval is the head and founder of the Illuminati Society. He was once Sir Percival, a knight of the Round Table of King Arthur. He became immortal after Camelot's fall by drinking from the Holy Grail. In the 7th century, one hundred years after the fall of King Arthur's kingdom, the man who would be known as Mr. Duval founded the Illuminati. He remained the immortal leader of the organization to this day. In 1996, soon after the Hunter's Moon incident, Mr. Duval phoned David Xanatos, probably to inquire as to what he knew of it. Xanatos decided not to answer. The repercussions of this were never seen.
Mr. Duval lives in Carbonek, the castle of the Holy Grail, along with his estranged wife, Blanchefleur. He pays some perpetual price for his sins.
Other than being immortal, nothing is known of Mr. Duval's abilities.