Naya Daur (transl. The New Era) is a 1957 Indian Hindi-language social drama film directed and produced by B. R. Chopra. It was written by Akhtar Mirza. It stars Dilip Kumar, Vyjayanthimala in lead roles, along with Ajit, Jeevan, Johnny Walker, Chand Usmani, Nazir Hussain, Manmohan Krishna, Leela Chitnis, Pratima Devi, Daisy Irani, Radhakishan form an ensemble cast. The film narrates the story of Shankar and Krishna, two best friends who fall for the same woman, Rajni.

For this film, Dilip Kumar won the Filmfare Award for Best Actor for the third time in a row, being his fourth overall. The film was later dubbed in Tamil as Pattaliyin Sabatham (The Proletariat's Vow) in 1958. Naya Daur also inspired Aamir Khan's Academy Award nominated film Lagaan (2001).

Naya Daur was the second-highest grossing Indian film of the year 1957 and also the second-highest grossing Indian film of the decade, behind Mother India (1957). At the time of its release, it briefly became the highest grossing Indian film ever; later being surpassed by Mother India (1957). By many sources, it remains one of the top 10 highest-grossing Indian films of all time when adjusted for ticket-price inflation. It became the highest-grossing sports film ever at the time of its release and remains one of the highest ticket-selling sports film, despite its release only being in India.