Thinker is one of the three men who travel the Purelake in search of Hoid. He has introduced himself with a different name, but Ishikk has nicknamed him Thinker, (correctly) assuming the name provided him is false. His traveling companions give their names as Temoo and Vao.
Thinker was described by Ishikk as thoughtful, with Alethi-like light tan skin, but wrongly shaped eyes and accent. For these, Ishikk decided he was certainly not Alethi. He spoke the Selay language worse than his two companions, and usually stayed quiet.