Geraldine "Gerry" Plunkett Dillon (1891–1986) was an Irish republican and member of Cumann na mBan, best known for her memoir All in the blood.

She was a friend of Michael Collins, who she met through Joseph in 1915 to help her when she had been left to manage the family finances and property while her mother was visiting the United States.

[1][7] On Easter Sunday 23 April 1916, she married Thomas Dillon, a chemistry lecturer she had met in University College Dublin, in Rathmines Church.

The wedding ceremony attracted the attention of the British forces, with a pair of "G-men" removed from the church by O'Connor and the Plunkett brothers.

As Thomas was a chemist, it was planned that he would be placed in charge of any chemical factories the Irish Volunteers captured to manufacture munitions and explosives, but this did not come to fruition.

[5][6] The last time Dillon saw her brother was as she left the hotel when he was blowing up an empty tram on North Earl Street with a homemade bomb.

[8] After Joseph's execution, the Plunkett siblings remained active in organisations such as the Irish Republican Army and Cumann na mBan.

Her husband spent a great deal of the period of 1916 to 1922 imprisoned or hiding from the authorities due to his republican activities, including an internment from May 1918 to January 1919 in Gloucester prison.

[11] They initially lived in Dangan House and later in Barna,[12] where it was used for Sinn Féin Court sessions with her husband presiding as judge.

[2] Dillon was arrested on Easter Monday 28 March 1921, and was imprisoned in Galway Gaol for three months after she was caught carrying literature from the White Cross.

[1] Ó Brolcháin recounts some of Dillon's achievements in the preface to her edited memoir, including delivering a paper in the Royal Irish Academy in 1916 and contributing to the Encyclopedia Britannica for the article on dyes.

[3] Dillon held a large collection of family papers, which contained documents from 1850, as well as keeping her own detailed notes and diaries up to her death in 1986.