Mary Ellen Spring Rice (14 September 1880 – 1 December 1924) was an Irish nationalist activist during the early 20th century.
Spring Rice was born into an aristocratic Anglo-Irish family in London. She was the daughter of Thomas Spring Rice, 2nd Baron Monteagle of Brandon, and a great-granddaughter of the British Chancellor of the Exchequer, Thomas Spring Rice. Her maternal grandfather was the bishop, Samuel Butcher. She was brought up on the family's Mount Trenchard estate overlooking the River Shannon. It was a progressive, liberal household and independence of thought was encouraged. So too was the Gaelic culture and, at home, Spring Rice and her brothers were taught how to speak fluent Irish.
Before the First World War, Spring Rice hosted many Irish nationalist and Conradh na Gaeilge meetings at her home, and she became a close friend of Douglas Hyde and her cousin Nelly O'Brien. During 1913 and 1914, Spring Rice was actively involved in gun-running, most notably the Howth gun-running.
This involved helping to ship weapons to be used in an Irish uprising from Germany into Ireland. Together with Molly Childers, she raised £2,000 towards the purchase of 900 Mauser rifles from Germany, many of which were used in the 1916 Easter Rising. Spring Rice sailed on the Asgard to collect the guns and helped to unload them in Ireland.