Major Guy Temple Montacute Larnach-Nevill, 4th Marquess of Abergavenny, JP, DL (15 July 1883 – 30 March 1954) was a British peer. Guy was the eldest son of Lord George Montacute Nevill and his wife Florence Mary Soanes. He married Isabel Nellie Larnach (d. 5 November 1953), the only child of James Walker Larnach, on 30 October 1909, and had three children: