Layla Hassan is the Animus user who becomes the playable modern protagonist in Assassin's Creed Odyssey.
Layla is an Abstergo Industries employee who defects and joins the modern Assassin movement. After the events of Assassin's Creed Origins, she uses an upgraded Animus to explore the memories of a Spartan mercenary living during the Peloponnesian War. Those memories form Odyssey's ancient Greek campaign.
The modern-day sections show Layla working with allies including William Miles and researchers from the Assassin team. Her investigation of the artifact called the Staff of Hermes Trismegistus links the ancient storyline to the series' continuing present-day conflict. Odyssey's historical protagonist can be Kassandra or Alexios, depending on the player's choice, but Layla is the fixed modern-day character.
Desmond Miles is the modern protagonist of the first several main entries, while Rebecca Crane is a technical specialist and not Odyssey's central Animus user. Bishop is a codename used by the modern Assassin network. These distinctions matter because the series moves between historical memories and a continuing contemporary plot.