The FitzGerald dynasty is a Hiberno-Norman or Cambro-Norman dynasty, and have been Peers of Ireland since at least the 14th century. The dynasty has also been referred to as the Geraldines. They were established by the conquest of large swathes of Irish territory by the sons and grandsons of Gerald FitzWalter of Windsor (c. 1075 – 1135). Gerald was a Norman Castellan in Wales, and is the male progenitor of the Fitzgerald dynasty ("fitz", from the Latin "fils" indicating "sons of" Gerald).
Gerald's Welsh wife Nest ferch Rhys (c. 1085 – before 1136) is the female progenitor of the Fitzgeralds. She was the daughter of Rhys ap Tewdwr, last King of Deheubarth. Through her the Fitzgeralds are descended from the Welsh rulers of Deheubarth as well as related to the Tudors who are descended from the same Welsh royal line. Consequently, the Fitzgeralds are cousins to the Tudors (Tewdwrs) through Nest and her Welsh family.
In his poetry, Henry Howard, Earl of Surrey, referred to Elizabeth FitzGerald (1527–89) as "Fair Geraldine".