Harlaw is one of the isles of the Iron Islands. The arms of the house refer to an occasion where ten men were hanged in the same day. The Mryes and the Kennings were once fierce rivals of the Harlaws, but they were eventually beaten down to vassals. The only member of the house to appear is Pinchface Jon Myre, who commands at least a dozen longships.
Information about House Myre that reveals spoilers from the books.