Jason of Thessalonica (Greek: Ίάσων ό Θεσσαλονικεύς), also known as Jason of Tarsus, was a Jewish convert and early Christian believer mentioned in the New Testament in Acts 17:5–9 and Romans 16:21.
Jason is venerated as a saint in the Orthodox and Roman Catholic traditions. His feast day is 12 July in the Roman Catholic Church, 28 April in the Slavic Christian tradition, and 29 April in the Greek Christian tradition. His feast is celebrated on the 3rd of Pashons in the Coptic Orthodox Church and in eastern Christian traditions he is commemorated on 4 January among the Seventy Apostles.