- "A chalice is merely a vessel for libation, for good or ill."
Adha (unknown – 1190) was a woman from the Middle East who possessed mysterious powers. She was in fact the "Chalice", commonly known as an ancient "artifact" that held powers similar to the Pieces of Eden.
In 1190, the Chalice was sought after by both the Knights Templar and Levantine Assassins, unaware that it was a person rather than an object. She was discovered by Altaïr Ibn-La'Ahad, an Assassin and former acquaintance, and aided him in thwarting the Templars' plans before being taken captive by them. She was subsequently deported to an unknown location and later murdered.
The Chalice was known to either be a holy artifact, or the descendant and heir of Jesus Christ.  According to Rashid ad-Din Sinan, whoever had the Chalice could unite all factions under them, granting them victory over all, and allowing them to rule the Holy Land. Seeing the danger of such an artifact, the Mentor sent one of his Assassins, Altaïr Ibn-La'Ahad, on a mission to retrieve it.
His search led him to the Temple of Sand, though Altaïr discovered only an empty golden chest. This prompted him to assume that it had already fallen into Templar hands, and so he traveled to Jerusalem.
Rescue and captureEdit
Discovering that the Chalice was being kept under Templar watch in the Holy City, Altaïr infiltrated their fortress and soon found Adha. Though he was absolutely surprised upon identifying her as the Chalice, he rescued her nonetheless.
Shortly afterwards, Adha informed him that the Templars had bribed Harash, the second-in-command of the Assassins, to betray their Order; to which Altaïr decided to seek him out at the Assassin fortress of Alep. Though he planned to kill the traitor and run away with Adha, upon completing his task, Adha was kidnapped by Basilisk, leader of the Templar Order.
Pursuing them to a port in Tyre, Altaïr fought his way onto Basilisk's ship at the head of the fleet, killing several Templar Knights and Basilisk himself. However, he discovered that Adha was being held on a different ship, which escaped before Altaïr could catch up to it. He returned to shore and, seeing the Templar ship far off in the distance, called out to Adha, promising to her that he would find her one day.
- "I had thought Adha would be the one to lead me to rest, that I might lay down my blade and live as a normal man. But now I know such dreams are best left to sleep..."
- ―Altaïr, in his Codex.[src]
In 1191, during Altaïr's preparations to assassinate Abu'l Nuqoud in Damascus, an Assassin informant asked him "Any news of Adha since she left?" When Altaïr remained silent, as always with informants, he continued with "No? How sad. I'm sure you'll find her someday."
Though the circumstances of Adha's death are unclear, Altaïr wrote in his Codex that he chased Adha's captors across the sea, but only caught up to them in time to hold Adha's lifeless body in his arms and see the terror in her unblinking eyes. He went on to state that he had hunted down and exacted vengeance on those that had killed her, though this had brought him no comfort, nor joy.
- Though not explicitly mentioned, the fact that Altaïr and Adha knew each other by name upon first meeting in Assassin's Creed: Altaïr's Chronicles suggested that they had met at least once before.
- An e-mail on the conference room computer of Abstergo Industries' Roman facility mentioned the Chalice, and questioned whether or not it was a real Piece of Eden. It also noted that the search for it would be called off until more evidence of its existence could be found.
- Adha means "sacrifice" in Arabic.