An entry for Back to Middle-earth Month 2010 at SWG: Queen Berúthiel of Gondor. She apparently was of Black Númenorean descent and from an inland city south of Umbar. Her marriage to King Tarannon, presumably, was arranged for political reasons.She was the nefarious, solitary, and loveless wife of Tarannon, twelfth King of Gondor (Third Age 830-913) and first of the "Ship-kings", who took the crown in the name of Falastur "Lord of the Coasts," and was the first childless king (...). Berúthiel lived in the King's House in Osgiliath, hating the sounds and smells of the sea and the house that Tarannon built below Pelargir "upon arches whose feet stood deep in the wide waters of Ethir Anduin;" she hated all making, all colours and elaborate adornment, wearing only black and silver and living in bare chambers, and the gardens of the house in Osgiliath were filled with tormented sculptures beneath cypresses and yews. She had nine black cats and one white, her slaves, with whom she conversed, or read their memories, setting them to discover all the dark secrets of Gondor, so that she knew those things "that men wish most to keep hidden," setting the white cat to spy upon the black, and tormenting them. No man in Gondor dared touch them; all were afraid of them, and cursed when they saw them pass. (...) Her name was erased from the Book of the Kings ("but the memory of men is not wholly shut in books, and the cats of Queen Berúthiel never passed wholly out of men's speech"), and that King Tarannon had her set on a ship alone with her cats and set adrift on the sea before a north wind. The ship was last seen flying past Umbar under a sickle moon, with a cat at the masthead and another as a figure-head on the prow.
(J.R.R. Tolkien, Unfinished Tales of Númenor and Middle-earth)
Another footnote states that there also is a connection between Tarannon's childlessness and Berúthiel's cats, though no further elucidation is given in the UT. Her cats have also become famed for finding their way home, Tolkien mentioning again that she (...) trained them to go on evil errands by night, to spy on her enemies or terrify them
, and Aragorn stating in the Lord of the Rings that Gandalf is surer of finding the way home in a blind night than the cats of Queen Berúthiel.
Anyway. I hope I did her some justice.