Daya Bai (born Mercy Mathew) is an Indian social activist from Kerala, working among the tribals of central India.

[2] She left Pala, Kerala at the age of 16 to become a nun,[3] and later gave up her habit, to work for the tribal population in the midlands of India.

She has been delivering inspirational speeches, holding satyagrahas and campaigns to press local authorities to open schools and empower neglected villages in the interior and tribal Madhya Pradesh.

Daya Bai, who practises the theology of liberation, settled down among the Gonds of Chhindwara district in Madhya Pradesh.

[6] Ottayal or 'One Person,' is an hour-long documentary on Daya Bai by Shiny Jacob Benjamin.