Katharine Parnell, known before her second marriage as Katharine O'Shea, and usually called Katie O'Shea by friends and Kitty O'Shea by enemies, was an English woman of aristocratic background whose decade-long secret affair with Charles Stewart Parnell led to a widely publicized divorce in 1890 and his political downfall.

Charles Stewart Parnell was an Irish nationalist politician who served as a Member of Parliament (MP) in the United Kingdom from 1875 to 1891, Leader of the Home Rule League from 1880 to 1882, and then of the Irish Parliamentary Party from 1882 to 1891, who held the balance of power in the House of Commons during the Home Rule debates of 1885–1886. He fell from power following revelations of a long-term affair, and died at age 45.