Wikipedia
Caoránach
In Irish folklore, Caoránach was said to be the mother of demons and devils who was banished by Saint Patrick to Loch Dearg in Donegal, Ulster. Another story states that Loch Dearg ("red lake") was named for the blood of Caoránach issuing from an old witch's thigh bone when it was slain by Fionn mac Cumhaill.