A Fremen housekeeper for House Atreides in their Arrakeen palace. Mapes is the first Fremen to test Lady Jessica and realize that she is Bene Gesserit. The housekeeper is a stern and honorable individual, warning Paul that there is traitor in House Atreides to repay him for saving her life from a hunter-seeker droid. Dr. Yueh kills Mapes when he betrays the Atreides to the Harkonnens.