In the 2016 film Assassin's Creed, Michael Fassbender plays the modern-day character Callum Lynch.
Callum is a convicted criminal who is recruited by Abstergo Industries, the modern face of the Templar Order. Through the Animus, he relives the genetic memories of his Spanish ancestor Aguilar de Nerha, an Assassin active during the Spanish Inquisition. The memory sessions are intended to help Abstergo locate the Apple of Eden.
The film uses an original protagonist rather than directly adapting a game's playable hero. Callum's modern-day storyline and Aguilar's historical storyline are connected through ancestry, but Aguilar is not simply Callum under another name. Fassbender portrays both characters.
Desmond Miles is the central modern-day protagonist of the first several mainline games, which is why he is a frequent incorrect answer. Daniel Cross and William Miles are also associated with the wider game mythology, but neither is the film's protagonist. The film was directed by Justin Kurzel and released in December 2016.