Cognitive entities native to Roshar, manifestations of natural forces, emotions, and concepts given form by human perception. Lesser spren appear as small, often visible phenomena - flamespren dance in fires, windspren play in breezes, fearspren pool around the frightened. Higher spren - honorspren, cryptics, cultivationspren, and others - are sapient beings capable of forming Nahel bonds with humans to create Knights Radiant. In the Physical Realm, bonded spren can manifest as Shardblades.