Clothru

Clothru was, according to medieval Irish legend, the daughter of Eochu Feidlech, a High King of Ireland, and the sister of queen Medb of Connacht and Ethniu.

[2] The next day, according to legend, her brothers were indeed killed, and when Lugaid was born, he was their heir.

[3] Lugaid later also became a High King of Ireland, thus Clothru's incest preserved the line of succession.

Incest features further in Clothru's story: she is said to have then slept with Lugaid herself, conceiving Crimthann Nia Náir,[4] who later also became a High King of Ireland.

The island of Inchcleraun (Irish Inis Cloithrinn) in County Longford takes its name from her.