Nater Guru (English: The main culprit) is a 2003 Indian Bengali language drama film directed by Haranath Chakraborty. Based on Samaresh Basu's famous novel of the same name, the film stars Ranjit Mallick, Jeet, Moushumi Chatterjee and Koel Mallick in her debut. It was successful at the box office.Nater Guru revolves around four main leads—Shashi Bhushan, a bookie in Kolkata race course who always gets defeated in the challenges; Sulochona, Shashi's wife, who keeps herself mutually separated from her husband becoming bored of his involvement in race course; Manisha, their daughter who gets troubled when her mother wants to meet her love interest, Durgadas; and Rabi, a mechanic who is hired to be the false Durgadas in front of Sulochona, by the advice of Shashi's adviser.

The soundtrack and background score of the film was composed by S.P Venkatesh, while the cinematography was by V. Prabhakar with editing by Swapan Guha. It was a super hit at the box office, with a successful run consisting of 165 days, in theatres.