Eithne and her sister Sodelb are two relatively obscure Irish saints from Leinster who are supposed to have flourished in the 6th century. They are commemorated together in the Irish martyrologies on 29 March, though 2 and 15 January were also marked out as feast-days. The 17th-century scholar John Colgan believed that a Life written for them had been witnessed in c. 1490 by Cathal Óg Mac Maghnusa (d. 1498), whom he regarded as the author of additions to the Félire Óengusso (see below). Although nothing of the kind has come to light, they do make cameo appearances in the Lives of two better known 6/7th-century saints, Áedan and Moling, both bishops of Ferns.