Altaïr Ibn La-Ahad, meaning "The Flying One, Son of None" in Arabic, an assassin and one of Desmond Miles' ancestors who lived in the Holy Lands during the Crusades.A member of the "Assassin Brotherhood," Altaïr was a master assassin whose status was revoked after he failed a mission in which he broke all three tenets of the Assassin's Creed which are as follows: "Stay your blade from innocent flesh," "Hide in plain sight," and "Never compromise the brotherhood."
Altair is the main protagonist of Assassin's Creed, and in the game you assume control of Altair under the premise of reliving the dreams of Desmond's ancestor. Altair's downfall, as illustrated in cutscenes at the beginning of the game, is entirely due to his arrogance and lack of respect for the ways of his Brotherhood. Throughout the game Altair learns more and more of his world, and in doing so gains new insights and a healthy respect and understanding far beyond the narrow perspective he has when we first meet him. This character development is a critical part of the unfolding plot and eventually challenges everything he was raised to believe.
 Physical Appearance
Altair is dressed in all white, as a disguise to blend in with monks and friars of various faiths. However, his garb has a distinctive flair that sets him apart to the discerning eye. His hood hides his identity in a deeper cowl than necessary, and his robes are close fitting and do no inhibit quick movement. He wears sturdy brown leathers and sports an elaborate belt upon which he fastens his main long blade. On his forearms he wears arm guards, from which his left arm can extend a hidden dagger. This dagger is used by Altair, which allows him to be more discrete in his assassinations.
 Appearance and Game Mechanics Criticisms
As mentioned, Altair's appearance is quite distinct, as is his unique swagger. How the Templars, guards, and other enemies of Assassin's Creed fail to pick out such a distinctly different "monk" is a mystery left only to one's imagination. Also to consider are why a monk can openly wear a long scabbard and arm guards without attracting attention. No other religious NPCs in the game have any accouterments remotely resembling armor or weaponry on their persons.
As an assassin, it can be assumed that Altair is significantly stronger than the average person due to the many acrobatic movements he is able to employ. He is able to climb even the tallest buildings barehanded without a harness as well as jump long distances, both of which are invaluable strengths when trying to run and hide from the enemy. Altair is also an impeccable swordsman capable of engaging several enemies in combat simultaneously. Moreover, he's also proficient at using other weapons as well, such as his hidden dagger and throwing knives. One of Altair's most prominent skills is stealth, which will play a major role in completing the majority of tasks and favors assigned to him. Finally, Altair has a unique ability called Eagle's Vision, which allows him to discern allies from enemies by a blue or red aura, respectively.
Nothing is known about Altaïr's background information, including where or exactly when is was born (though current information suggests around 1165-1166 AD). His parents and relatives (if any) are unknown.