Rashtriya Swayamsevak Sangh (RSS) or National Patriotic Organization is a right-wing charitable, educational, volunteer, Hindu nationalist, non-governmental organization. It is the world's largest voluntary non-governmental organization. RSS states that its ideology is based on the principle of selfless service to India.

The RSS was founded on Vijayadasami Day, 27 September 1925 as a social organization to provide character training through Hindu discipline, to unite the Hindu community in overcoming caste-based divisions, to counter British colonialism in India, and to suppress Muslim separatism. The organization initially drew inspiration from European right-wing groups during World War II. Gradually RSS has grown into an extremely prominent Hindu nationalist umbrella organization and by the 1990s, allied organizations had established numerous schools, charities and clubs to spread its ideological beliefs.

It has been criticised as an extremist organization and as a paramilitary group. It has also been criticised when its members participated in anti-Muslim violence and has since formed militant wing Bajrang Dal. Along with other extremist organizations the RSS was involved in a wide range of riots, often inciting and organizing violence against Christians and Muslims.