Ilaiyaraaja (born Gnanadesikan) is an Indian film composer who works predominantly in the South Indian cinema since the late 1970s. Regarded as one of the finest music composers in India, Ilaiyaraaja is also an instrumentalist, conductor, singer, and a songwriter. He has composed more than 5000 songs and is the only composer in the history of cinema to provide film scores for more than 1000 films, particularly being acclaimed for hisbackground scoring. His songs and background score played a very crucial role in the success of many films.

He integrated folk—in Tamil—and introduced western musical sensibilities into the South Indian musical mainstream. Ilaiyaraja is also known for creating music by fusing symphonic orchestration with traditional Indian instrumentation, often performed by Budapest Symphony Orchestra. In 1993 he organised a full symphony performed by the Royal Philharmonic Orchestra in London and thus became the first Indian to compose a full symphony, with Ravi Shankar being the only other Indian to do so. He is also the first Asian to compose a full symphony performed by the Royal Philharmonic Orchestra. He has won four Indian National Film Awards (the highest film honor in India); three for Best Music Direction and one for Best Background Score—tied with A. R. Rahman for the most by any composer—and is a recipient of Padma Bhushan, awarded by the Government of India.

In the 2000s, he composed a variety of non-film music, including religious and devotional songs, an oratorio, and world music. He is usually referred to by the title Isaignani (English: Musical Genius), or as The Maestro. Ilaiyaraja is a gold medalist in classical guitar from Trinity College of Music, London. In 2003, according to an international poll conducted by BBC, people from 155 countries voted his composition Rakkamma Kaiya Thattu from the 1991 film Thalapathi as fourth in the world's top 10 most popular songs of all time. He was also nominated in the Best Indian album Music Awards category at US based Just Plain Folks Music Organization, which is the largest grassroots music organization in the world, and stood third for his "Music Journey: Live in Italy". In 2012 he received the Sangeet Natak Academi Award for his creative and experimental works in music field.

Popular world cinema portal Taste of Cinema placed Ilaiyaraja at the 9th position in its list of 25 greatest film composers in the cinema history. In a poll conducted by CNN-IBN celebrating 100 years of Indian cinema in 2013, Ilaiyaraaja was voted the greatest music composer of India with a maximum of 49%.