Which game introduced the modern-day protagonist Layla Hassan?

Assassin's Creed Origins introduced the modern-day protagonist Layla Hassan.

Layla is an Abstergo researcher who operates independently after developing an experimental Animus device. In Origins, she uses the machine to explore the memories of Bayek and Aya in Ptolemaic Egypt, eventually becoming involved with the modern Assassin conflict.

She returns as the modern-day lead in Assassin's Creed Odyssey and Assassin's Creed Valhalla. This makes Origins the beginning of a connected modern-day arc spanning those three games, even though the historical protagonists change from Bayek and Aya to Kassandra or Alexios, and then to Eivor.

Layla is not the modern protagonist of earlier entries such as Assassin's Creed III, which centers on Desmond Miles, or Syndicate, which uses a more player-defined modern identity. Origins was released in 2017 and marked a major shift toward role-playing systems as well as a new modern-day character.