Mary Forbes, Countess of Granard (c.1677 – 4 October 1765), formerly the Hon. Mary Stewart, was the wife of George Forbes, 3rd Earl of Granard. She was born in Ireland, the daughter of William Stewart, 1st Viscount Mountjoy, and his wife, the former Mary Coote. Mary Stewart's first husband was Phineas Preston of Ardsallagh, County Meath; they married in 1692 and had four children: Following Phineas Preston's death, Mary married Forbes in 1709, when he was a naval officer. They had three children: She died a few months after her husband, aged around 88.