The Apple of Eden is the powerful Isu artifact that appears throughout Assassin's Creed.
In the series' mythology, the Apples are Pieces of Eden created by the Isu, an advanced civilization that existed before humanity's recorded history. They can influence human minds, create illusions, and interact with other advanced devices. Their powers explain why these artifacts are coveted by both Assassins and Templars.
The Apple of Eden is not one single unique object in every storyline. The games depict multiple Apples, and different characters possess or seek them at different points. The first Assassin's Creed prominently features an Apple held by Robert de Sablé's forces and later handled by Altaïr.
The artifact is often confused with other Pieces of Eden, such as the Apple-like devices' associated artifacts, the Sword of Eden, or the Staff of Hermes Trismegistus. The Apple is also connected to the series' reinterpretation of the biblical forbidden fruit, but the games present it as Isu technology rather than ordinary magic.