Sir Timothy O'Brien, 1st Baronet (1787 – 3 December 1862) was an Irish Whig, Independent Irish Party and Repeal Association politician, and merchant. He was the son of Timothy O'Brien and his wife (née Madden). In 1821, he married Catherine Murphy, daughter of Edward Murphy, and they had at least five children: Timothy (died 1869); John (died 1869); Kate (died 1894); Ellen (died 1899); and Patrick (1823–1895). Outside of his political career, O'Brien was also a Justice of the Peace and a Deputy Lieutenant.