Ion Ionel Constantin Brătianu was a Romanian politician, leader of the National Liberal Party (PNL), Prime Minister of Romania for five terms, and Foreign Minister on several occasions; he was the eldest son of statesman and PNL leader Ion Brătianu, the brother of Vintilă and Dinu Brătianu, and the father of Gheorghe I. Brătianu. Ion I. C. Brătianu's political activities after World War I, including part of his third and fourth term, saw the unification of the Old Romanian Kingdom with Transylvania, Bukovina and Bessarabia. In 1923, he was elected an honorary member of the Romanian Academy.

Ion Constantin Brătianu was one of the major political figures of 19th-century Romania. He was the son of Dincă Brătianu and the younger brother of Dimitrie, as well as the father of Ionel, Dinu, and Vintilă Brătianu. He also was the grandfather of poet Ion Pillat.