Master of the Tower

The Master of the Tower was a high-ranking Templar who commanded a Templar base, the Jerusalem Tower. Strangely, he is very similar in appearance to an Assassin, but his robe is colored black with blue stripes. He probably studied the Assassins and their creed for his own knowledge, which he even passes to a student of his own.

In Assassin's Creed: Altaïr's Chronicles, Altaïr finds his way to the tower and its Master, an Assassin-like figure who is actually a high-ranking Templar. Altaïr fights his way up the tower, killing the Master's guards and his student. Finally, he reaches the Master himself. At the top of the tower, Altaïr confronts the Master, who tries to get him to join the Templars in their quests. Altaïr refuses the offer, kills the master and takes the map the Temple of the Sand

Trivia

 * He shares his model (black-colored "assassin") with Harash.
 * In the picture, you can see Altair saying that the templars wear "strange garbs". This is ironic, as the Master uses a garb very similar to his (or, more precisely, the assassins).