Rowland FitzEustace, 1st Baron Portlester was an Irish peer, statesman and judge. He was one of the dominant political figures in late fifteenth-century Ireland, rivalled in influence probably only by his son-in-law Garret FitzGerald, the "Great" Earl of Kildare.

Castlemartin is the name of a historic house and estate, and the townland in which they sit, on the banks of the River Liffey in Kilcullen, County Kildare, Ireland. Formerly a key estate of the Eustace family, it was for many years the home of media magnate Tony O'Reilly, and his wife, Chryss Goulandris, but was bought in 2015 by John Malone, an Irish American. The estate includes major stud farm and cattle breeding operations, a restored medieval church and an icehouse.