Ullur S. Parameswara Iyer, born Sambasivan but popularly known as Ullur, was an Indian poet of Malayalam literature and a historian. He was one of the modern triumvirate poets of Kerala in the first half of the 20th century, along with Kumaran Asan and Vallathol Narayana Menon. Umakeralam, a mahakavya, and Kerala Sahitya Charitram, a comprehensive history of the Malayalam language are two of his most important works.