The ancient order opposed by the Assassins throughout Assassin's Creed is the Templars.
The series presents the Assassins and Templars as rival secret societies whose conflict stretches across many historical periods. The Templars generally seek order and control, while the Assassins defend human freedom and independent choice. Their methods, goals, and individual members vary by era, but the ideological rivalry is the central thread linking the games.
The fictional Templar Order is inspired partly by the historical Knights Templar, a medieval Christian military order founded in the early twelfth century. Assassin's Creed transforms that historical reference into a conspiracy that survives for centuries. As a result, real historical Templars and the game's fictional organization should not be treated as identical.
Major Templar figures include Robert de Sablé in the first game, Rodrigo Borgia in Assassin's Creed II, Haytham Kenway in Assassin's Creed III, and several leaders in later titles. Some characters begin as Templars or oppose the Assassins for personal reasons, making the conflict more complicated than a simple hero-versus-villain story.