Brigid Lyons Thornton (13 May 1896 – 15 November 1987) was an Irishwoman who was a member of Cumann na mBan, an officer in the Irish Free State Army and a doctor.

[1][2] From a young age she was involved in the nationalist movement, starting with selling badges and flags at the funeral of O'Donovan Rossa in 1915.

[2] At a young age, Brigid moved to Longford to live with her uncle Frank McGuinness, later a senator,[2] and his wife Kate, who paid for her secondary school education.

Brigid Lyons was a medical student and, as a member of Cumman na mBan, was involved with the Irish Volunteers during 1916.

[1] Brigid Lyons married Captain Edward Thornton on 10 October 1925, in Dublin, at the Chapel of St Kevin in the Pro Cathedral.

Meanwhile her husband resided in Switzerland for most of the winter months, working as a lawyer, and their relationship was maintained through letter writing and yearly visits to Ireland.

Lyons was involved in Sinn Féin and Cumann na mBan, although women were limited by their male counterparts in the scope of their revolutionary activities.

Later she became a first lieutenant in 1922 and was commissioned by Michael Collins as the first and only woman to be accepted as officer in the Free State Army when a new, permanent medical service was established.

She was an avid educator of women on the importance of hygiene in the development of children and factors of disease that flourished in the impoverished slums of the inner city and surrounding suburbs.

[2] In her youth Thornton had expressed the passion to become a teacher, but as women's role in society changed and constraints became less stringent, she could study medicine and pursue greater participation in this area.