Nilavu Suduvathillai () is a 1984 Indian Tamil-language film, directed by K. Rangaraj. The film stars Sivakumar, and Radhika in the lead roles, N. Viswanathan and V. Gopalakrishnan. It was released on 18 May 1984.
Ravi falls in love with Radhika. Soon his love turns to sadness when he learns that she is his boss's daughter, masquerading as an ordinary girl only to assess his suitability as her partner.
The film was launched along with song recording at Prasad Studios in 1983. The song "Paari Jaadham" was filmed in February 1984.
The music was composed by Ilaiyaraaja. This was his first collaboration with Rangaraj. The song "Naalum En Manam" was reused twice by him: as "Prema Ledhani" for Telugu film Abhinandana (1988) and again in Tamil as "Premai Enathu Oor" for Vattara Vazhakku (2023).