Ronald Wayne Langacker (born December 27, 1942) is an American linguist and professor emeritus at the University of California, San Diego. He is best known as one of the founders of the cognitive linguistics movement and the creator of Cognitive Grammar. He has also made significant contributions to the comparative study of Uto-Aztecan languages, publishing several articles on historical Uto-Aztecan linguistics, as well as editing collections of grammar sketches of under-described Uto-Aztecan languages.