Arunthathiyar is a Scheduled Caste community found in the state of Tamil Nadu, India. The term has two distinct usages: for the purposes of the state government's positive discrimination program, in 2009 it was designated an umbrella term for the Arunthatiyar, Chakkiliyan, Madari, Madiga, Pagadai, Thoti and Adi Andhra (Adi Dravida) communities; while the Office of the Registrar-General, which administrates the census of India, does not recognise all of those communities as one.
The 2001 Census of India reported that there were 771,659 Arunthathiyar in Tamil Nadu, being 6.5 per cent of the Scheduled Caste population of the state.
At the 2001 census, 64 per cent of the Arunthathiyar population lived in rural areas of Tamil Nadu, which according to the Office of the Registrar-General makes them "comparatively an urbanised SC community". Their literacy rate of 54 per cent was less than other Scheduled Castes such as the Paraiyar, Adi Dravida and Pallan but higher than the Chakkiliyar.