O'CONOR, CHARLES (1804-1884), American lawyer, was born in the city of New York on the 22nd of January 1804, and was the son of Thomas O'Conor (1770-1855), who in 1801 emigrated from Roscommon county, Ireland, to New York, where he devoted himself chiefly to journalism. The son studied law, was admitted to the bar in 1824, and soon won high reputation in his profession. He was United States district attorney for New York in 1853-1854. In politics an extreme States'-Rights Democrat, he opposed the coercion of the South, and after the Civil War became senior counsel for Jefferson Davis on his indictment for treason, and was one of his bondsmen; these facts and O'Conor's connexion with the Roman Catholic Church affected unfavourably his political fortunes. In 1872 he was nominated for the presidency by the “Bourbon” Democrats, who refused to support Horace Greeley, and by the “Labour Reformers”; he declined the nomination but received 21,559 votes. He took a prominent part in the prosecution of William M. Tweed and members of the “Tweed Ring,” and published Peculation Triumphant, Being the Record of a Five Years' Campaign against Official Malversation, A.D. 1871-1875 (1875). He removed to Nantucket, Massachusetts, in 1881, and died there on the 12th of May 1884.