Stevens, Thaddeus (1792–1868), a United States statesman. Throughout a long and controversial career, the “Old Commoner,” as Stevens was called, fought for the poor and oppressed. He was an outspoken foe of slavery and was firmly committed to racial equality. After the Civil War, as the leading Radical Republican in the House of Representatives, Stevens helped win passage of key measures of the Congressional reconstruction plan for the South, which was designed to protect the social and political rights of the newly freed blacks. He was a harsh critic of President Andrew Johnson, who believed Stevens was too lenient toward the South, and helped bring about Johnson's impeachment.

Stevens was called “the Evil Genius of the Republican Party” by his opponents, who charged him with trying to ensure the supremacy of his party and of Northern commercial interests. Although he was caustic, uncompromising, and at times vindictive, most scholars have come to view him as an unswerving defender of democracy and freedom, motivated chiefly by principle.

Stevens was born in Danville, Vermont. He had a congenitally deformed foot and often was in frail health. In 1814 he graduated from Dartmouth College. While practicing law in Gettysburg and Lancaster, Pennsylvania, he participated in local politics. Stevens first served in the House of Representatives as a Whig, 1849–53, and earned a reputation as an abolitionist. After helping to organize the Republican party in Pennsylvania, he was returned to Congress, serving from 1859 until his death.