C. K. Ramakrishnan Nair (1917 – 16 September 1994), popularly known as C.K. Ra, was an Indian painter, writer, and teacher of fine arts. An advocate of creative freedom, Ramakrishnan Nair was credited with bringing modernism in Kerala painting and heralded the 'Ra phase' in Kerala painting. He served as the superintendent of the Trivandrum School of Arts and later became the chairman of Kerala Lalita Kala Akademi.