The House of Nádasdy, also spelled Nadasdy in English, is a major Hungarian aristocratic family whose roots reach into the Middle Ages. The house motto is, "Si Deus pro nobis quis contra nos," ("If God is for us, who can be against us?"). The Nadasdy family made a large contribution to the development of Hungarian printing. The Nadasdy Hussars, a regiment named after the family, developed a strategy incorporating lightly armed and fast-moving cavalry that was internationally adopted.
The name is first encountered in the early part of the 13th century, that of Imre (descendant of Darabos de Nádasd) and his sons, Stefánd, Tódor, and Valkomer. Another important member, deceased before 1275, was Simon Nádasdy. Frequently mentioned in family records between 1324 and 1376 is Petà  Gersei, who was married to Margit Hidvégi, is considered the progenitor of the family "Pethà  de Gerse". In 1229, Petan sold most of his land to a member of the family Nádasdy. The buyer and his three sons, Vencel/Venceslav, Raszló/Vraslav and László/Ladislav, now partially used the predicate of Pethenegh. Laszlo Nádasdy of Pethenegh (c. 1236) is the progenitor of main line Nádasdy.
Of its many holdings, the family held the in Sárvár, Hungary, the Csejte Castle, in ÃÂachtice, Slovakia which is situated on a hill adjacent to a nature reserve, and the Nádasdy Castle in Nádasdladány, Hungary.