Twelve Apostles of Jesus Christ, according to the New Testament. He is informally called doubting Thomas because he doubted Jesus' resurrection when first told, (in the Gospel of John), followed later by his confession of faith, "My Lord and my God", on seeing Jesus' wounded body.
Traditionally, he is said to have travelled outside the Roman Empire to preach the Gospel, travelling as far as India. According to tradition, the Apostle reached Muziris, India in AD 52 and baptized several people, founding what today are known as Saint Thomas Christians or Nasranis. After his death, the reputed relics of Saint Mesopotamia in the 3rd century, and later moved to various places. In 1258, some of the relics were brought to Abruzzo in Ortona,Italy, where they have been held in the Church of Saint Thomas the Apostle. He is often regarded as the Patron Saint of India, and the name Thoma remains quite popular among Saint Thomas Christians of India.
More on St. Thomas the Apostle: http://www.americancatholic.org/features/saints/saint.aspx?id=1433