Rusky Castle was a small tower standing on an island in Loch Rusky although nothing of it now remains.
In 1460 Isabella, Countess of Lennox and eldest daughter of Donnchadh, Earl of Lennox, died. Her sons and husband had predeceased her, as had her two sisters, Elizabeth and Margaret, and so the Earldom of Lennox was divided between her sister’s heirs. Agnes Menteith, a granddaughter of Margaret and daughter of Murdoch Menteith of Rusky, inherited a quarter of the Earldom. She married John Haldane of Gleneagles.
Agnes’s sister, Elizabeth Menteith, who married John Napier of Merchiston, also inherited a quarter of the Earldom, while Sir John Stewart of Darnley inherited the other half of the Earldom. In 1493 Sir John reached an agreement with John Haldane of Gleneagles and his son, James, whereby they renounced their claims over the superiority and tenandry of their quarter of the Earldom.