The term Phoenix Park Murders is used to refer to the assassination in 1882 of the second and third in command of the British Dublin Castle government of Ireland by the Irish National Invincibles.

On 6 May 1882, the senior Irish civil servant, the Permanent Under Secretary, Thomas Henry Burke and the newly appointed Chief Secretary for Ireland, Lord Frederick Cavendish, were brutally stabbed to death using surgical knives, as they walked though the Phoenix Park in Dublin en route to the Viceregal Lodge, the 'out of season' residence of the Lord Lieutenant of Ireland. The then Lord Lieutenant, John Poyntz Spencer, 5th Earl Spencer, described suddenly hearing screams, before witnessing a man running to the Lodge grounds shouting "Lord Frederick Cavendish and Mr. Burke are killed". Responsibility for the assassinations was claimed by a small republican organisation called the Invincibles. In the aftermath, the Irish nationalist leader Charles Stewart Parnell offered to resign from parliament in protest at what he called "these vice murders", an offer turned down by the British Prime Minister, William Ewart Gladstone.

In 1887 Parnell was accused by the British newspaper The Times of complicity in the plot to murder Cavendish and Burke. An investigation cleared the Irish leader of the accusation, which was revealed to be the work of an embittered journalist, Richard Pigott , who committed suicide.