Leandros

Leandros (died 1511) was a member of the Templar Order and the leader of a small Byzantine faction.

By 1511, his forces had overrun the Assassins' fortress of Masyaf. When Ezio Auditore da Firenze visited the city, his forces attacked him and eventually managed to capture him. They later led him to be executed, and Leandros personally tied the noose around Ezio's neck. As soon as he did so, though, Ezio lunged back at him and managed to escape. Later, Leandros was assassinated by Ezio on one of Masyaf's rooftops.

Source

 * Assassin's Creed: Revelations Preview