Tollin is the name of the Dwarf that accompanied Gloria Larsen to Fablehaven. They both arrived wearing masks. When Gloria Larsen went back in time, she told the others that she had made a journey to Istanbul to send a message to Hank, and a Dwarf awaited her there. He apparently used to work at the Living Mirage. He helped the others use the Translocator to transport to the Living Mirage, and it was later hinted that he betrayed them.
- Keys to the Demon Prison (Fablehaven #5)