Augusta Mary Monica Crichton-Stuart, Marchioness of Bute, DBE (19 August 1880 – 16 May 1947) was a daughter of Sir Alan Henry Bellingham, 4th Baronet and Lady Constance Julia Eleanor Georgiana Noel, daughter of the 2nd Earl of Gainsborough.
She married John Crichton-Stuart, 4th Marquess of the County of Bute, son of John Patrick Crichton-Stuart, 3rd Marquess of the County of Bute and Hon. Gwendolen Mary Anne Fitzalan-Howard, on 6 July 1905 at Castle Bellingham, Kilsaran, County Louth, Ireland. Both her father and her father-in-law were noted converts to Roman Catholicism.
After her marriage Augusta Bellingham was styled as Marchioness of Bute and her married name became Crichton-Stuart. She and her husband had seven children.
She was invested as a Dame Commander of the Order of the British Empire (DBE) in 1918. She was also invested as a Dame of Grace, Order of St. John of Jerusalem, and decorated with the Médaille de la Reine Elisabeth of Belgium.
She died in 1947, aged 66.