The protagonist introduced in Assassin's Creed Origins is Bayek of Siwa.
Bayek is a Medjay from the Siwa Oasis in ancient Egypt. The game follows his investigation into a conspiracy affecting Egypt and shows how his experiences help lead to the formation of the Hidden Ones, the organization that later becomes known as the Assassin Brotherhood.
Assassin's Creed Origins was released in 2017 and is set primarily during the final years of the Ptolemaic Kingdom. Its story includes Cleopatra VII, Julius Caesar, and Ptolemy XIII, while its open world covers locations such as Alexandria, Memphis, Siwa, and the Sinai region.
Aya of Alexandria is Bayek's wife and an important playable character, but she is not the principal protagonist. Origins is also distinct from Assassin's Creed Odyssey, which is set earlier in ancient Greece and features Kassandra or Alexios as the player character.