Croom or Crom Castle, also called the Castle of Crom, is a historic castle in the town of Croom, County Limerick, that is notable for its occupation as one of the principal residences of the Kildare branch of the FitzGerald dynasty. Their ancient war cry and motto "Crom a Boo", or in Irish "Crom Abú" or "Crom forever", comes from the strategic fortress. Before the FitzGeralds it was the site of an earlier fortress of the O'Donovans.