Altaïr Ibn-La'Ahad (1165–1257) was a Syrian Assassin during the Middle Ages and, from 1191 until his death, the Mentor of the Assassins in the Levant. His name means 'The Bird - Son Of The One And Only' and is also the name of the brightest star in the constellation Aquila. He was born on the 11th of January 1165 and is known for not following the creed.

Source: Assassin Creed Wikia, "Altaïr Ibn-La'Ahad," available under the CC-BY-SA License.