Maria Thorpe

Maria is the steward (and possibly lover or daughter) of the Templar, Robert de Sable.

Robert foresees his assassination. Eight of his comrades are dead. Sure his assassination is planned to occur at an outdoor event in Jerusalem, he leaves Maria to impersonate him and flees to Arsuf. Sure enough, Altaïr comes, and a great swordfight ensues. Maria, impersonating Robert, is a surprisingly excellent fighter, but Altaïr defeats her. When he realizes that it is not Robert, but a woman, he spares her life and hurries to Arsuf to finish Robert once and for all. What happens to her afterwards is unknown.

There is no information about her before or after the ambush, however she seemed to be of a high rank in the Knights Templar noting that she was able to match Altaïr's sword skills and that she'd be chosen for such an important mission. She also hints that she knows about the piece of Eden, which leaves speculations that she might actually be a lover or daughter of Robert De Sable. This would help explain the reason as to why a woman would be allowed such a high place in the Templars. There are further speculations that letting her go may have been a massive mistake by Altaïr, for with her leadership and possible knowledge of the Pieces of Eden, she may have re-established the Templars after Altaïr's obliteration of their ranks and slaying of their leaders.

Final Words
Altaïr: I would see your eyes before you die.

(Altaïr rips off the helm, only to see Maria's face).

Maria: I sense you expected someone else.

Altaïr: What sorcery is this!?

Maria: ''No sorcery: we knew you'd come. Robert needed to be sure he'd have time to get away''.

Altaïr: So he flees!?

Maria: ''We cannot deny your success. You have laid waste to our plans: first, the treasure, then our men. Control of the Holy Land slipped away, but then he saw an opportunity, to reclaim what has been stolen, to turn your victories to our advantage!''

Altaïr: ''Al Mualim still holds your treasure, and we've routed your army before! Whatever Robert plans, he'll fail again!''

Maria: Ah, but it's not just Templars you'll contend with now!

Altaïr: Speak sense!

Maria: Robert rides for Arsuf to plead his case, that Saracen and Crusader unite...against the Assassins!

Altaïr: ''That will never happen! They have no reason to!''

Maria: ''Had, perhaps. But now you've given them one: nine, in fact. The bodies you've left behind, victims on both sides. You've made the Assassins an enemy in common and ensured the annihilation of your entire order! Well done!''

Altaïr: Not nine, eight.

Maria (confused): What do you mean?

Altaïr: ''You are not my target. I will not take your life. You're free to go, but do not follow me!''

Maria: ''I don't need to. You're already too late!''

Altaïr: We'll see.

Model
Maria is likely based on Marguerite de Sable, the daughter of Robert de Sable and Clemence de Mayenne, born before Robert's promotion to Grand Master of the Knights Templar.