Ailill Finn, son of
Art mac Lugdach, was, according to medieval Irish legend and historical tradition, a
High King of Ireland. In the
Lebor Gabála Érenn, he succeeded to the throne when his father was killed by
Fíachu Tolgrach and his son
Dui Ladrach. He ruled for nine years. Two years into his reign, Fíachu Tolgrach was killed in battle against
Airgetmar, son of
Sírlám. The men of
Munster, led by Ailill's son
Eochu and Lugaid, son of
Eochu Fíadmuine, then drove Airgetmar into exile overseas. After seven years Airgetmar returned to Ireland and killed Ailill with the help of Dui Ladrach and his son Fíachu, but was unable to seize the throne, which was taken by Eochu.