Kathleen Florence Lynn (28 January 1874 – 14 September 1955) was an Irish Sinn Féin politician, activist and medical doctor. She was born to a Dublin Church of Ireland family and educated in England and Germany before graduating as a doctor in 1899 from the Royal University of Ireland.
An active suffragette, labour activist and nationalist, Lynn was a member of the Irish Citizen Army and chief medical officer during the 1916 Easter Rising. For her part in the rising, she was imprisoned in Kilmainham Gaol, with her friends Constance Markiewicz, Madeline ffrench-Mullen and Helena Moloney. In 1923, Lynn was elected to Dáil Éireann as a Sinn Féin Teachta Dála (TD) for the Dublin County constituency at the 1923 general election. In accordance with Sinn Féin abstentionist policy of the time, she did not take her seat in Dáil Éireann. She lost her seat at the June 1927 general election. She unsuccessfully contested the August 1927 by-election for Dublin County.
Lynn's medical career was defined by her work at Saint Ultan's Hospital for Infants, which she established in Dublin in 1919, with a group of female activists. Lynn's work with Dublin's inner city poor had convinced her of the need for a hospital to provide medical and educational facilities for impoverished mothers and infants. Earlier in her career Lynn has experienced discrimination in applying for hospital position due to her gender, and Saint Ultan's was the only hospital in Ireland entirely managed by women. Saint Ultan's Hospital grew rapidly, and from 1937 became the centre for BCG vaccination in Ireland. The hospital closed in 1984.
Lynn lived in Rathmines from 1903 to her death in 1955, sharing her home with her friend and confidante Madeline ffrench-Mullen. Lynn died on 14 September 1955, and is buried in the family plot at Deansgrange Cemetery. In acknowledgement of the role she played in the 1916 Rising and the Irish War of Independence, she was buried with full military honours.
Lynn's personal diaries for the period 1916–1955, and the administrative papers of Saint Ultan's Hospital are available in the Royal College of Physicians of Ireland's archive.