Baselios Marthoma Mathews III (born 12 February 1949) is the present Primate of Malankara Church, Catholicos of the East and Malankara Metropolitan and the Metropolitan of the Diocese of Kandanad West and the Diocese of Kottayam Central of the Malankara Orthodox Syrian Church. He was enthroned as the 22nd Malankara Metropolitan and 9th Catholicos of the Malankara Church on 15 October 2021 at St. Peter and St. Paul's Church, Parumala, succeeding Baselios Marthoma Paulose II.

He was ordained as a deacon in 1976 and then as a priest in 1978 by Baselios Mathews I.[2] On 30 April 1991 he was consecrated to the order of Episcopos.[4] In 1994, he was consecrated as a metropolitan of the Diocese of Kandanad West. Also he has been serving as the assistant metropolitan of the Diocese of Idukki since 2019.

He is a teacher at Orthodox Theological Seminary, Kottayam since 1984. He taught Christology in the graduate and post-graduate levels while guiding a number of doctoral theses. He has authored several scholarly books and articles in the field of Theology. He has also served as the Executive Secretary to the Holy Episcopal Synod. The Holy Episcopal synod held at Devalokam Aramana nominated him as the successor to the Catholicos of the East & Malankara Metropolitan on 16 September 2021.[2]

He organized several charitable projects at the diocesan level.[6][7] Mar Pachomios Charitable Society, formed in the memory of his predecessor Joseph Mar Pachomios, Metropolitan of Kandanad, runs over a dozen charitable projects including; Pratheeksha Bhavan, Prasanthi Bhavan, Prathyasa Bhavan, Pradanam Centre, Pramodam Project, Prasannam Bhavan, Prakasam Institute of Special Education and Prathibha Products.

In October 2021, the Holy Synod and Managing committee designated him as the new Malankara Metropolitan and Catholicos of Malankara Church succeeding Baselios Marthoma Paulose II who passed away in July 2021. He was enthroned as the 22nd Malankara Metropolitan during the Malankara Association that took place on 14 October 2021 at St. Peter and St. Paul's Church, Parumala. He was enthroned as Catholicos of the Apostolic Throne of Saint Thomas on 15 October 2021 by the Holy Synod of Malankara Church. The chief celebrant of the enthronement service and Holy Eucharist was Kuriakose Mar Clemis who is the senior metropolitan of Malankara Orthodox Syrian Church