The Reol have a unique natural defense; one of their bodily secretions is used to create false memories and illusions when it comes into contact with a living creature. Their appearance are very tall, lanky bipedal creatures with thick strands of hair and dark black eyes. Their heads appear almost skeletal in shape. The Reol have also decided not to embrace technology to the extent that no other species have. They were only encountered once by the Tau'ri when they met a member named Kaiael, who took the appearance as a fifth member of SG-1, Lt Tyler. (SG1: "The Fifth Man")