Krishnankoil Venkadachalam Mahadevan (14 March 1918 – 21 June 2001) was an Indian composer, singer-songwriter, music producer, and musician known for his works in Tamil, Telugu, Malayalam, and Kannada films. He is best known for his contributions in works such as Manchi Manasulu (1962), Lava Kusa (1963), Thiruvilaiyadal (1965), Saraswathi Sabatham (1966), Kandan Karunai (1967), Thillana Mohanambal (1968), Adimai Penn (1969), Balaraju Katha (1970), Athiparasakthi (1971), Sankarabharanam (1979), Saptapadi (1981), Sirivennela (1986), Sruthilayalu (1987), Pelli Pustakam (1991), and Swathi Kiranam (1992).

A contemporary of M. S. Viswanathan and T. K. Ramamoorthy, starting his career in 1942 with Manonmani, Mahadevan scored music for over six hundred feature films, spanning four decades, and has garnered two National Film Awards, three Andhra Pradesh state Nandi Awards, a Tamil Nadu State Film Award, and a Filmfare Award South. He was also conferred the title of "Thirai Isai Thilagam" (Pride of Cine Music Directors) in Tamil cinema. His assistant Pukazhenthi is credited to have usually writing the score and arranging the orchestra, after Mahadevan composes a tune.