| Honorific-Prefix: | Bishop |
| Rajarethinam Arokiasamy Sundaram | |
| Bishop Emeritus of Tanjore | |
| See: | Tanjore |
| Appointed: | 4 February 1953 |
| Term Start: | 19 March 1953 |
| Term End: | 12 September 1986 |
| Successor: | Packiam Arokiaswamy |
| Ordination: | 24 February 1941 |
| Consecration: | 19 March 1953 |
| Consecrated By: | Louis Mathias |
| Birth Name: | Rajarethinam Arokiasamy Sundaram |
| Birth Date: | 10 June 1905 |
| Birth Place: | Megathur |
| Religion: | Catholic |
Rajarethinam Arokiasamy Sundaram (RA Sundaram) was born on 10 June 1905 in Megathur of Valampuri of Thanjavur. He was ordained a priest 24 February 1941. He was appointed first Bishop of Thanjavur on 4 February 1953. He served nearly 33 years as Bishop of Thanjavur. He died on 28 August 1998.[1] Besides his pastoral works, the bishop's multidimensional approach on the promotion of education and socio-cultural economic measures benefited different sections of the society.
Sundaram was first son of Rajarathinam and Lourdu Mary, in devout family of Valampuri, Thanjavur. He finished his school education in Thanjavur and Palayamkottai. He joined St. Joseph's College, Thiruchirapalli for higher studies.
After finishing his studies, Sundaram decided to work for a few years and then join the seminary. For a short period, he taught English at the St. Xavier's college, Palayamkottai. He got an offer to work as a professor of physics at St. Joseph's College, Darjeeling. After three years, Sundaram joined the minor seminary at Santhome. Sundaram joined the Urban College in Rome to enable his ordination in six years. He was an outstanding seminarian there at Urban college and a member of the literary association, editing and publishing newsletters and compering programs in the Radio Vatican.
Sundaram was ordained priest in 1941. Fr. Sundaram celebrated his first two mass in the St. Paul's Cathedral and St. Peter's Basilica in Rome.
Fr. Sundaram was appointed assistant Parish Priest at Vallam, Thanjavur. Fr. Sundaram was appointed Headmaster of Santhome High School, Mylapore. His efforts bring this school as one of the best schools in the city, within a short period. The Diocese of Thanjavur was created on 22 November 1952 and Fr. Sundaram assumed charge in 1953 as First Bishop of Thanjavur.He formed two social service societies at Thanjavur and Pudukkottai that helped uplift the status of the poor. Some of their schemes had been unique and innovative and one among them was providing lands to the landless. Because of his efforts, there is phenomenal increase in the number of educational, religious and social welfare institutions in and around Thanjavur. Even today, the diocese of Thanjavur has the highest number of boarding homes for students in India.