Bayek is the Medjay from Siwa who becomes the central character in Assassin's Creed Origins.
Bayek serves as a protector of his community in Ptolemaic Egypt. A personal tragedy draws him into a campaign against a secretive group whose activities threaten Egypt's political order. His investigation gradually develops into the foundation story of the Hidden Ones, the organization that later becomes the Assassin Brotherhood.
Bayek's wife, Aya, is also a major figure in the narrative. The two work together while navigating the rivalries surrounding Cleopatra, Julius Caesar, and Ptolemy XIII. The game uses these historical events as the setting for a fictional origin story rather than presenting Bayek as a documented historical person.
Senu, Bayek's eagle, helps him scout locations and identify targets, while Khemu is Bayek's son. Those names are therefore associated with Bayek's story but are not alternative names for its protagonist.