Nada Klaić (21 July 1920, Zagreb – 2 August 1988, Zagreb) was a Croatian historian. She was a Croatian medievalist of the 20th century. A substantial part of the work was devoted to criticism of medieval sources.
Nada Klaić was born in Zagreb, the granddaughter of the historian Vjekoslav Klaić. She was a university professor and a prominent Croatian medievalist, graduated at the Faculty of Philosophy of the University of Zagreb, the same faculty where she was involved in teaching for 45 years. She started her teaching and scientific career at the Faculty's Department of History in 1943, to become a full professor of the Croatian medieval history in 1969. This position she held until her death in 1988.
Since 1946, when she took her doctor's degree with the thesis Političko i društveno uređenje Slavonije za Arpadovića (Political and Social Organization of Slavonia under the Árpád dynasty), she spent several decades engaged in researching Croatian medieval history. Nada Klaić gathered the results of her extensive analytical investigations, published first in journals and proceedings, and monographs and surveys of Croatian history.
She researched the period from the arrival of the Slavs (see Migration Period) until the 19th century. Under the early influence of M. Barada, Lj. Hauptmann, B. Grafenauer and J. Šidak, she contributed to the Croatian Medievalism by writing papers about social history. The book History of the Yugoslav Peoples II (1959) includes her comprehensive overview of the history of Croatia in the Early Modern Times, including elements of economic and social history.
She paid special attention to the history of cities, as shown by several studies and books: Zadar in the Middle Ages until 1409 (with Ivo Petricioli, 1976), Zagreb in the Middle Ages (1982), Notes on Vukovar in the Middle Ages (1983), Trogir in the Middle Ages: Public Life of the City and its Inhabitants (1985), Koprivnica in the Middle Ages (1987).