In Irish mythology, Deichtine or Deichtire was the sister of Conchobar mac Nessa and the mother of Cúchulainn. Her husband was Sualtam, but Cúchulainn's real father may have been Lugh of the Tuatha Dé Danann.

In one version of the story she was Conchobar's charioteer. When a flock of birds descended on Emain Macha and ate all the grass, the Ulstermen decided to to hunt them, and they set off after them in their chariots. They chased them until night fell, and it began to snow, so they decided to seek shelter. They found a house and were welcomed in by the young man who lived there. His wife was in labour at the time, but he showed them hospitality and served them food and drink. His wife gave birth to a baby boy, and at the same time a horse outside the house gave birth to two colts. The Ulstermen went to sleep, but when they woke up they found themselves at the Brú na Bóinne (Newgrange). The house, the man and his wife had vanished, but the baby and the two colts remained. Deichtine took the boy as her foster-son and they returned to Emain.

Soon after the boy fell ill and died. Deichtine took a drink, and a tiny creature leaped from the cup into her mouth. When she fell asleep, Lugh appeared to her and told her it was his house they had stayed in that night, and that his child was in her womb. She married Sualtam and gave birth to a son.

In another version, Deichtine disappeared from Emain Macha. As before, a flock of birds came to Emain and led the Ulstermen to Lugh's house, but the wife in labour wife was Deichtine. They woke up at the Brú na Bóinne, Lugh and the House had vanished, but Deichtine and the baby remained. They returned to Emain and Deichtine married Sualtam.