There was an idol on the Mag Sleact in Cavan County, Ulster devoted to Crom Cruach. His statue was of gold and surrounded by twelve smaller, stone statues.
Parents sacrificed one third of the children to him on Samhain in exchange for a fertile growing season.
He was said to have been introduced by King Tigernmus.
St. Patrick cursed and destroyed the idol and stopped his worship.
He is mentioned in the 6th century Dinnshenchas in the Book of Leinster, as well as the Tripartite Life of Patrick.
Alternative: Cromm Cruac ("bloody crescent"), Cenn Cruaic ("bloody head"), rid-iodal h-Eireann ("the king idol of Ireland")