martinus or marinus was briefly co-emperor of the byzantine empire from september/october 641–september/october 641. martinus was the son of emperor heraclius and empress martina. after the death of heraclius, the byzantine empire was left to two of martinus brothers, constantine iii and heraklonas. heraklonas was left the sole emperor, under the regency of martina, after constantine died of tuberculosis, although partisans of constantine alleged that martina had constantine poisoned. one such partisan, valentinus, led troops to chalcedon to force martina to make constans ii, the son of constantine, co-emperor. in late september/october 641, martina raised martinus to co-emperor, as well as tiberius and constans. valentinus seized constantinople regardless, and deposed martina and heraklonas, and cut off martinus nose and emasculated him, before exiling him to rhodes.