Daniel Wolsey Voorhees (September 26, 1827 – April 10, 1897) was an American lawyer and politician who served as a United States Senator from Indiana from 1877 to 1897. He was the leader of the Democratic Party and an anti-war Copperhead during the American Civil War.

Voorhees was born in Liberty Township, Butler County, Ohio, of Dutch and Irish descent. He was the son of Stephen Pieter Voorhees and Rachel Elliott. During his infancy his parents moved to Fountain County, Indiana, near Covington. In 1849, he graduated from Indiana Asbury University (now DePauw University) in Greencastle, Indiana. He then studied law, was admitted to the bar in 1850, and began to practice in Covington, Indiana. In 1857, he moved to Terre Haute, where he continued to practice law. From 1858 to 1861, Voorhees was U.S. District Attorney for Indiana.

From 1861 to 1866 and 1869 to 1873, Voorhees was a Democratic representative in Congress. During the American Civil War he was an anti-war Copperhead, albeit not as radical as Clement Vallandigham. He was accused of membership in the Knights of the Golden Circle, an organization promoting Southern conquest of much of Central America and the Caribbean as a pro-slavery empire.

Historian Kenneth Stampp has captured the Copperhead spirit in his depiction of Voorhees of Indiana:

There was an earthy quality in Voorhees, "the tall sycamore of the Wabash." On the stump his hot temper, passionate partisanship, and stirring eloquence made an irresistible appeal to the western Democracy. His bitter cries against protective tariffs and national banks, his intense race prejudice, his suspicion of the eastern Yankee, his devotion to personal liberty, his defense of the Constitution and state rights faithfully reflected the views of his constituents. Like other Jacksonian agrarians he resented the political and economic revolution then in progress. Voorhees idealized a way of life which he thought was being destroyed by the current rulers of his country. His bold protests against these dangerous trends made him the idol of the Democracy of the Wabash Valley. [Stampp, p. 211]

After the Civil War, Voorhees was a staunch opponent of Black civil and political rights. He believed that whites' temporary loss of total political control in places where they were not in the majority made them "as very a slave in the hands of a brutal overseer as any negro ever driven in a cotton-field, and that he had no more power under existing laws to protect his personal freedom than an African bondsman on the auction-block before the war...the liberation of one race had been followed by the enslavement of another."

Voorhees complained repeatedly about what he perceived as the North's unjust treatment of the vanquished South, claiming it would be a challenge to find a group in history treated worse than white Southerners during Reconstruction.

In his "Plunder of the Eleven States" speech made to the U.S. House of Representatives on March 23, 1872, Voorhees outlined the crimes he perceived to be committed upon the South by the North: