Ramasamy Ganesan (17 November 1920 – 22 March 2005), better known by his stage name Gemini Ganesan, was an Indian actor who worked mainly in Tamil cinema. He was referred to as the Kaadhal Mannan (King of Romance) for his romantic roles in films. Ganesan was one of the "three biggest names of Tamil cinema", the other two being M. G. Ramachandran and Sivaji Ganesan. While Sivaji Ganesan excelled in dramatic films and M. G. Ramachandran was popular as an action hero, Gemini Ganesan was known for his romantic films. A recipient of the Padma Shri in 1971, he had also won several other awards including the Kalaimamani, the MGR Gold Medal, and the Screen Lifetime Achievement Award. He was one of the few college graduates to enter the film industry then.

Gemini Ganesan made his debut with Miss Malini in 1947 but was noticed only after playing the villain in Thai Ullam in 1953. After playing the lead role in Manam Pola Mangalyam (1954), he finally acquired star status. However, unlike Sivaji Ganesan or Ramachandran, Gemini Ganesan was not a stage performer and was never involved in politics. In his long film career spanning over five decades, Ganesan acted in more than 200 films. His performances on the screen were enhanced by successful playback singers such as A. M. Rajah and P. B. Sreenivas. Despite his celebrated film career, Ganesan's personal life, particularly his marriages to multiple women over the years, including famous Indian actress Savitri, has often been a subject of criticism. He had eight children, including actress Rekha.