What was Raja Ram Mohan Roy famous for?

Raja Ram Mohan Roy is famous for spearheading the religious and social reforms in India that called for the abolition of Sati and remarriage of widows. He founded the Brahmo Samaj in 1828. 

It was one of the most influential religious movements in India and made a significant contribution to the making of modern India.

For further reading check the following articles:

• Peasant Movement and Tribal Uprisings in India
• British Empire
• Different land revenue systems