Legendary early king of Ireland, who ruled with his kinsmen (sometimes brothers, sometimes cousins) Áed Ruad and Cimbáeth. Each takes a seven-year term in a twenty-one-year cycle. Seven magicians, seven poets, and seven lords of Ulster guarantee that the agreement will be kept. When Áed Ruad dies, his daughter Macha (2) is elected to rule. Díthorba and Cimbáeth initially oppose her, but Cimbáeth makes peace with her and later marries her; she kills Díthorba. The five sons of Díthorba are forced by Macha to work as slaves in the building of Emain Macha.