Jacob Barker (1779–1871) was an American financier and lawyer.
He was born in Swan Island, Maine, in 1779, of Quaker parentage. He went to New York at the age of 16, engaged in trade, and soon amassed a considerable fortune. Beginning in 1811, Fitz-Greene Halleck was employed by him for twenty years. Early in the War of 1812 he was instrumental in securing a loan of $5,000,000 for the national government. In 1815, he founded the Exchange Bank of New York. He was a member of the New York State Senate in 1816. Subsequently he became interested in many other large financial institutions in the city, including the Life and Fire Insurance Company, on the failure of which in 1826 he, with a number of others, was arrested on a charge of conspiracy to defraud. At first he acted as his own lawyer, however, eventually eminent attorneys Benjamin F. Butler and Thomas Addis Emmet (1764–1827) were counsels for his defense. The jury disagreed on the first trial and convicted Barker on the second trial; but an appeal was granted and the indictment was finally quashed.
He removed to New Orleans in 1834, became prominent in financial circles, was admitted to the bar, and practiced with success in insurance cases. In the 1840s he collaborated with Rowland G. Hazard to secure the release of free African-Americans who were being illegally detained in Louisiana under the assumption they were escaped slaves. At the close of the American Civil War he was elected to the United States Senate, but Louisiana not having been readmitted to the Union, he was not allowed to take his seat. In 1867 he was declared bankrupt and spent the last few years of his life with his son in Philadelphia.
Barker published The Rebellion: Its Consequences and the Congressional Committee, Denominated the Reconstruction Committee, with their Action (1866).