Na. Muthukumar () is a Tamilpoet and lyricist, who writes lyrics for Tamil film songs.
Muthukumar began his career wanting to be a director and worked under Balu Mahendra for four years. But then he became a lyricist, beginning with the lyrics for the songs of the Tamil film Veera Nadai, directed by Seeman. Since then, he has written songs for more than 50 films, written lyrics for more than 700 songs and worked with almost every contemporary Tamil film music composer and is currently one of the most important and most busiest writer in the Tamil film industry. Mostly he has worked together with Yuvan Shankar Raja and wrote lyrics to the songs, he composed. He even turned dialogue writer for the Tamil film Kireedam (2007), directed by A. L. Vijay.
On 24 June 2006, he got married Jeevalakshmi at the JS Marriage Hall in Vadapalani in Chennai.