Colonel Nicholas Cusack (c.1638 – September 1726) was an Irish Jacobite politician and soldier.
[3] His brother-in-law Chief Justice John Keating, the brother of his wife Catherine, played a prominent role in the Parliament.
[4] During the Williamite War in Ireland, Cusack initially served as a captain in his uncle, Tyrconnell's, regiment of horse.
During the second Siege of Limerick, he was among the confidants of Patrick Sarsfield, 1st Earl of Lucan who encouraged the Jacobite commander to sue for peace.
He was outlawed later that year and fled to France where he served in the Irish Brigade of the French Royal Army.