What is the name of the Assassin's Creed organization before it is called the Brotherhood?

The Assassin's Creed organization before it is called the Brotherhood is the Hidden Ones.

Assassin's Creed Origins introduces the Hidden Ones as an organization founded by Bayek and Aya in ancient Egypt. They develop principles and methods that later become associated with the Assassin Brotherhood, including secrecy, resistance to oppressive control, and the protection of human choice. The name reflects their need to operate outside the authority of kings and empires.

Origins is therefore not simply a story about a fully formed medieval Assassin order. It explains how the movement begins after Bayek and Aya confront a powerful conspiracy. Later games show the organization evolving across different regions and historical periods until the familiar Assassin Brotherhood identity becomes established.

The Order of the Ancients is the opposing organization in Origins and is an early predecessor of the Templars. It is not an earlier name for the Assassins. The Brotherhood label appears in later franchise history, while the Hidden Ones belong specifically to the order's formative phase in the ancient world.