Rao Sahib Ayyathan Gopalan (3 March 1861 – 2 May 1948), popularly known as Darsarji and Darsar Sahib ("Darsar" means "doctor", derived from Latin word "docere" for doctor), was an Indian doctor, surgeon, professor, writer, philanthropist, social reformer, and Renaissance leader from Kerala. He is the founder of the Sugunavardhini movement (1900) and Depressed classes mission (1909) and also the leader and propagandist of Brahmo Samaj (1893) in Kerala. He denounced idol worship and fought to end those social practices in Kerala that he thought were unethical. Among his followers were Brahmananda Swami Sivayogi, Vaghbatananda, and Brahmavadhi P. Kunhiraman. Gopalan titled P. Kunhiraman as "Brahmavadhi" and Sivayogi as "Brahmananda Swami".