They are portrayed by Derek Mears and Aleks Paunovic.
Seven years before the beginning of the story, Annabeth Chase, Luke Castellan, Grover Underwood and Thalia Grace tried go to Camp Half-Blood while being pursued by two Cyclopes. When they had almost reached the camp, one of the Cyclopes threw a tree at them, injuring Grover. Luke helped him and Thalia decided to stay to hold off the Cyclopes, who went after her. She managed to wound one of them in the leg, but the other grabbed her and threw her away. As she lay dying, her father Zeus turned her into a pine tree, creating a magical barrier around the camp. The two Cyclopes went to attack the others before they entered in the camp, however they were stopped the barrier and tried to break it, without success.