Mary Kate Ryan (31 October 1878 – 18 July 1934) was an Irish academic and the first woman lecturer in University College Dublin's French Department as well as being a political activist who was involved in Ireland's Easter Rising, War of Independence, and Civil War.

[1] Mary Kate Ryan was born on 31 October 1878, in the townland of Tomcoole, near Taghmon, County Wexford.

[2][3][4] While living in Dublin and working in UCD, Ryan's house became a centre for nationalists and Irish cultural supporters.

She was an active member during the Easter Rising in Dublin, serving in the General Post Office during the week, and was jailed in Mountjoy Prison before being released on health grounds.

She fell out with her sister Min Ryan as her husband, Richard Mulcahy, was part of the Pro-Treaty government.

[2][3][4][9][10][15][16][17] After the Irish Civil War ended, Ryan was vice-president of the UCD Republican Club.

[2][3][4][9][10][18][1] In 1936, Seán O'Kelly married his late wife's younger sister, Phyllis Ryan, after gaining a papal dispensation to do so.