Devadass Ambrose Mariadoss is an Indian Catholic bishop serving the Roman Catholic Diocese of Thanjavur.
He was born on 6 October 1947 to Mariadoss and Ranjitham, a Catholic family from Ammapet in Thanjavur District of Tamil Nadu state.
After finishing his basic education at Appavu Thevar High School at Ukkadai, he joined St.
Mary's Minor Seminary to become a diocesan priest when the diocese was in a desperate need for the native priests and then he was sent to Sri Pushpam College, Poondi, along with F.
Antonysamy, the present bishop of Kumbakonam to do a pre-university course for his secular UG degree.
After finishing his secular studies, he was sent to St.
Paul's Seminary, Trichy for his priestly formation and for his philosophical (B.ph) and theological studies (B.Th.).
Eventually, he was ordained a priest on 5 August 1974 by Bishop Arokiasamy Sundaram, the first Bishop of Thanjavur.