The name of the house’s castle and its arms refer to the fact that the founder of the house killed a king. Kingsgrave sits near the Prince’s Pass, admist the mountains. The only members of the house to appear are Lord Dagos Manwoody who is the current head of the house, his sons Mors and Dickon, and his brother Ser Myles Manwoody.
Information about House Manwoody that reveals spoilers from the books.