The Old Ones are the main antagonists in Anthony Horowitz's fantasy thriller series The Power of Five. They are ancient incarnations of Evil led by the Demon King Chaos, who ruled Earth back ten thousand years in the past but were banished to another universe by the mysterious Five Gatekeepers. They now seek to return to the world and influence events from throughout the story. The Old Ones are based on the Great Old Ones of the writings of H.P. Lovecraft.