Which developer created the first Assassin's Creed game?

Ubisoft Montreal developed the first Assassin's Creed game.

The Montreal studio created the original title for Ubisoft, building the game's open-world technology, parkour system, combat, and historical environments. The project evolved from an idea connected to the Prince of Persia series before becoming a separate franchise.

The development team aimed to create a game centered on freedom of movement and historical immersion. Its design emphasized climbing buildings, blending into crowds, and observing targets before carrying out assassinations.

Ubisoft Montreal has remained closely associated with the franchise. Other Ubisoft studios later developed or co-developed entries, including Ubisoft Quebec for Assassin's Creed Odyssey and Ubisoft Sofia for Assassin's Creed Liberation. Those later studios do not change the original game's credited developer.