Liath Macha ("grey of Macha") and Dub Sainglend ("black of Saingliu") were the two chariot-horses of the hero Cúchulainn in the Ulster Cycle of Irish mythology.
Both horses appeared to Cúchulainn from the pool of Linn Liaith in the mountains of Sliab Fuait, a gift from either Macha of her sister the Morrígan. Cúchulainn leapt onto their backs, and they ran around Ireland for a day but could not throw him off, after which they were tame.
On the day of Cúchulainn's death, as his enemies gathered for battle, Liath Macha refused to allow Láeg, Cúchulainn's charioteer, to harness him to the chariot. He only relented for Cúchulainn himself, but wept tears of blood. He was hit by the second spear thrown by Lugaid mac Con Roí (the first had killed Láeg), and returned to the pool of Linn Liaith in the mountains of Sliab Fuait, where Cúchulainn had originally found him. The sons of Calatin had prophesied to Lugaid before he threw each spear that it would kill a king. When he challenged them each time, they responded that he had killed the king of charioteers and the king of horses. Dub Sainglend continued to pull the chariot, but Lugaid's third spear hit Cúchulainn, who fell out of the chariot. Dub Sainglend ran on, but Liath Macha returned to protect him, killing fifty with his teeth and thirty with each of his hooves. After Cúchulainn died, Liath Macha led Conall Cernach to his master's body. Conall pursued Cúchulainn's killers and avenged him.