Dyfan was an early Christian martyr who lived in southeastern Wales during the Roman or Sub-Roman period. Often identified as the protomartyr of Wales, he is the namesake of the location Merthyr Dyfan. While some historical accounts once linked him to the legendary baptism of King Lucius through the figure of St Deruvian, modern scholars have discredited this connection. His martyrdom is traditionally dated to approximately 180 AD, a timeline influenced by these earlier, now refuted, associations.