Altaïr Ibn-La'Ahad (Japanese: アルタイル・イブン・ラ・アハド Altaïr Ibn-La'Ahad, Arabic: الطائر ابن لا أحد) is a major character in Ubisoft's Assassin's Creed franchise and the main protagonist of the first installment of the series.
Altaïr is an ancestor of Desmond Miles, a modern-day American bartender and Assassin who is forced to use a contraption called the Animus to relive the memories of his ancestors. In the year 1191, during the Third Crusade, the Crusaders battle against the Saracens for control over the Holy City of Jerusalem. A member of the Assassin Brotherhood, Altaïr, along with two other Assassins, Malik and Kadar, botch an attempt to assassinate Robert de Sablé, Grand Master of the Knights Templar, in order to retrieve a treasure known as the Apple, one of many 'Pieces of Eden'. The failed mission results in Kadar's death and the amputation of Malik's left arm, although the latter succeeds in recovering the Apple. Learning of the failure, Altaïr's master, Al Mualim, admonishes him. Shortly after this, Altaïr fends off a group of Templars attacking their home village of Masyaf, partially redeeming himself, but Al Mualim soon orders him to assassinate nine individuals that he might fully redeem himself. Initially unbeknownst to him, these nine were comprised of high ranking members of the Templar order within the Holy Land, though Altaïr discovers this fact partway through his mission. After Altaïr dispatches all nine, Al Mualim takes the Apple of Eden for himself and uses its power to either kill or enslave those he deemed a threat. This includes Altaïr, who learned through Robert de Sablé's dying words that Al Mualim was also a Templar. After an ensuing duel, Altaïr kills Al Mualim, then burns the body and tells the onlookers of his treachery.
Now a hero to the entire order, Altaïr assumes the role of Mentor to restructure and improve their practices. After many years of training the next generation, studying the Apple and liberating nations from the Templars, Altaïr gains the status of a legend. However, this legacy would be jeopardized when the Order of Assassins was overthrown by his Brother and childhood rival, Abbas Sofian. Abbas has Altaïr's son Sef killed and the murder pinned on Malik, who had been serving as leader of the Order in Altaïr's absence on a mission against the rising threat of Genghis Khan. Learning of the truth, Altaïr returns to Masyaf with his family to confront Abbas, though a fight breaks out, resulting in his wife Maria being killed, and an aggrieved Altaïr fleeing Masyaf with his son Darim. Altaïr is not seen again for 20 years, during which Abbas takes control of the Assassin Order, which grows weak and lethargic in the face of mounting threats. Finally seeing no way to deal with this situation diplomatically, Altaïr enlists several other Assassins to go behind the Order's back and stage a coup against Abbas and his lieutenants.
After Abbas's death at the hands of Altaïr, the latter reassumes the title of Mentor, vowing to keep it that way. Altaïr would spend most of his twilight years writing the Codex, which chronicled his life, adventures, and moral code. This Codex would shape the lives of future Assassins in the series. In 1257, Altaïr entombs himself and his Apple within a secret library in Masyaf, shortly before a Mongolian invasion upon the castle, whose evacuation Altaïr had ordered prior. His remains would not be discovered until the year 1512, by his descendant and Assassin Mentor Ezio Auditore da Firenze, who, having lived a full Assassin's life himself, elects to leave the Apple within, but not before using it to commune with Desmond, the Apple delivering its message through the Animus.
As a costume
Altaïr's reveal trailer primarily makes reference to the maneuvers used by Assassins throughout the Assassin's Creed series. It begins with the Mii Swordfighter landing in a bird's nest on Skyloft, akin to the Leap of Faith, a move used to safely fall from great heights by landing on a soft material, most commonly a pile of hay. During the move, a faint screech from a bird of prey can be heard while the Assassin is airborne, which is reflected in the trailer. Following this, the Swordfighter is seen hanging from an edge in Gerudo Valley where Sheik stands near, then briefly getting up and back throwing Sheik into the chasm below, mirroring a similar move used when hanging on ledges to pull a near target downwards to their death with the assistence of the Hidden Blade. Afterwards, the Swordfighter confronts Robin, whose appearance resembles that of Al Mualim, Altaïr's mentor, wearing a dark cloak and wielding a sword, as well as another item. This mirrors an event near the end of Assassin's Creed, where Altaïr must confront his mentor to prevent him from further controlling the minds of the Masyaf populace at his will. The tome held by Robin represents the Apple of Eden, an item held by Al Mualim throughout the confrontation, with the casting of Arcfire resembling the Apple's strong, yellow glow.