The Templars are the secret society that opposes the Assassins throughout the Assassin's Creed series. Their long-running conflict is one of the franchise's central story elements.
The Templars generally seek order and control, while the Assassins defend the freedom of human choice. The series presents this opposition through historical organizations, political movements, and modern corporations rather than treating either side as a simple real-world equivalent.
In the modern-day storyline, Abstergo Industries serves as a major Templar front. The company develops the Animus and uses it to investigate genetic memories, while modern Assassins work to prevent the Templars from acquiring powerful First Civilization artifacts.
The historical Knights Templar existed during the Middle Ages, but the games turn them into part of a fictional global conspiracy. The term Crusaders refers broadly to participants in the Crusades and is not the series' name for the opposing secret order.