The Chevalier Tialys is a Gallivespian spy. A member of Lord Asriel's rebellion, he accompanied Lady Salmakia to watch over Will and Lyra on their journey. They are discovered amid the landing of Magisterium troops by zeppelin in the cave where Lyra is held captive by Mrs. Coulter. Despite initial animosity, particularly on Will's part, their presence is soon tolerated and accepted by the children. Their experience together in the Land of the Dead forms a close bond between the four travellers, realised upon Lady Salmakia's death.