William Nugent (Irish: Uilliam Nuinseann) (1550–1625) was a Hiberno-Norman Irish rebel in the 16th century Kingdom of Ireland, brother of Christopher, fourteenth baron of Delvin (Sixth Baron Delvin), and the younger son of Richard Nugent, thirteenth baron of Delvin, from whom he inherited the manor and castle of Ross in County Meath. His mother was Elizabeth Preston, daughter of Jenico Preston, 3rd Viscount Gormanston, and widow of Thomas Nangle, feudal Baron of Navan.