Rathnagiri Rahasya (transl. The secret of Rathnagiri) is a 1957 Indian Kannada-language adventure film, directed and produced by B. R. Panthulu, starring Udaykumar and Jamuna. The film was made simultaneously in Tamil as Thangamalai Ragasiyam, released in the same year, with Jamuna reprising her role. Most of the technical crew remained the same for both Tamil and Kannada versions.