Kollur Manjunatha Bhatta Rathnakar (11 April 1931 - 21 September 2010) was an Indian actor and director, known for his work in Kannada film industry.

He is best known for his comic roles in movies including Kanyarathna (1963), Satya Harishchandra (1965), Guru Shishyaru (1981), Hosa Belaku (1982) and Halli Meshtru (1992).

Rathnakar became a permanent member of Simha's troupe and went on to act plays with Rajkumar and Pandari Bai.

In his five decade career, Rathnakar has played variety of roles as teacher, singer, priest, palm reader, vendor in more than 300 films.

Rathnakar died on 21 September 2010 in Mysore, due to respiratory problems and other age related ailments.