S. Krishnamoorthy, better known by his screen name Madhan Bob, is a Tamil comedian and actor. He started his film career as a musician and then became an actor. Apart from appearing in supporting roles in Tamil films, he also appeared in the Sun TV comedy show Asathapovathu Yaaru as one of the judges. His debut film was Vaaname Ellai. He also taught music to M. M. Keeravani.

Bob was the eighth child in his family, so he was named Krishnamurthy, which also happened to be his uncle’s name. There was a lot of confusion in the house, so they changed his name to Madan. His's brother’s name is Padmanabhan aka Babu. Both started a music group called ‘Madan and Babu’. Soon, Babu became Bob, and that is how director K. Balachander introduced him in his first film.