Muriel MacDonagh (née Gifford; 18 December 1884 – 9 July 1917) was an Irish nationalist, and member of Inghinidhe na hÉireann.

Returning to Ireland, she trained at Sir Patrick Dun's Hospital, Dublin as a student nurse, but her health suffered from the work.

She was involved in the school meals programme of 1910 to 1911, took part in a 1914 Women's Franchise League fundraiser, appearing in a tableau vivant as Maeve, the Warrior Queen.

In 1908 she was introduced to Thomas MacDonagh by suffragette journalist Nora Dryhurst along with her sisters, Grace and Sidney, on a visit to St Enda's School.

Dryhurst advised Thomas to "fall in love with one of these girls and marry her", to which he replied laughingly "That would be easy; the only difficulty would be to decide which one".

Devastated by his death, and estranged from her parents due to their disapproval his involvement in the Rising, she lived with the Plunketts at Larkfield, Kimmage briefly, and then with relatives of her husband's in Thurles, County Tipperary.

[1] With two young children to support, she was nearly destitute, but like the other widows and orphans of the executed leaders of the Rising, they were aided by the Irish Volunteers Dependents' Fund, in her case with £250.