Krishna Raja Wadiyar IV (June 4, 1884-August 3, 1940, Bangalore Palace), also known popularly as Nalvadi Krishna Raja Wadiyar, was the ruling Maharaja of Mysore from 1902 till his death in 1940. He was son to Chamaraja X Wadiyar (ruling Maharaja of Mysore between 1881 and 1894).
He is regarded as one of the most celebrated rulers among the Indian States when India was still under British rule. At the time of his death, he was also one of the world's wealthiest men, with a personal fortune estimated in 1940 to be worth $400,000,000 which would be equivalent to $1,000,000,000 today.
He was a philosopher-king, who was seen by Paul Brunton as living the ideal expressed in Plato’s Republic. He has been compared to the Emperor Ashoka by the English statesman Lord Samuel. Mahatma Gandhi called him Rajarshi, or "saintly king", and his kingdom was described by his followers as Rama Rajya - an ideal kingdom akin to the rule of Lord Rama.
Krishna IV was the 24th ruler of the Wodeyar dynasty of Mysore that ruled over Mysore State from 1399 to 1950.
He was succeeded by Jayachamaraja Wadiyar Bahadur.