Ion Constantin Brătianu (Romanian pronunciation: [iˈon brətiˈanu]; June 2, 1821 – May 16, 1891) was one of the major political figures of 19th century Romania. He was 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.
Born to wealthy Argeș landowners in Pitești, the state of Wallachia, he entered the Wallachian Army in 1838, and in 1841 started studying in Paris. Returning to his native land, Brătianu took part, with his friend C. A. Rosetti and other young politicians (including his brother), in the 1848 Wallachian Revolution, and acted as prefect of police in the provisional government formed in that year.
The restoration of Imperial Russian and Ottoman authority shortly afterwards drove him into exile. He took refuge to Paris, and endeavoured to influence French opinion in favor of the proposed union and autonomy of the Romanian Danubian Principalities. In 1854, however, he was sentenced to a fine and three months' imprisonment for sedition, and later confined in a lunatic asylum; in 1856, he returned to Wallachia with his brother - afterwards one of his foremost political opponents.