Isaac (イザク, Izaku) is one of the main antagonists of Kamen Rider Saber. He was the most recent leader of the Sword of Logos and the final holder of the title Master Logos (マスターロゴス, Masutā Rogosu) who manipulated the Almighty Book to become Kamen Rider Solomon (仮面ライダーソロモン, Kamen Raidā Soromon).