Muirne or Muireann Muncháem ("beautiful neck") was the sister of Uirne and the mother of Fionn mac Cumhail in the Fenian Cycle of Irish mythology.
She had many suitors, but her father, the druid Tadg mac Nuadat, had foreseen that her marriage would lead to the loss of his home on the hill of Almu, so he refused them all.
Cumhal was killed in the Battle of Cnucha, but Muirne was already pregnant, so her father rejected her and told his followers to burn her.
Conn prevented this, and sent Muirne into the protection of Fiacal mac Conchinn and his wife, the druidess Bodhmall, who was Cumhal's sister.
Muirne left the boy in the care of Bodhmall and a warrior woman called Liath Luachra, who brought him up in secret in the forest.