Seth Wallace Cobb (December 5, 1838 – May 22, 1909) was a U.S. Representative from Missouri.
Born near Petersburg, Virginia, Cobb attended the common schools. Joined a volunteer company from his native county in 1861 and served throughout the Civil War in the Army of Northern Virginia. He moved to St. Louis, Missouri, in 1867 and was employed as a clerk in a grain commission house for three years. In 1870 became engaged in the same business on his own account. He served as president of the Merchants' Exchange in 1886. He served as president of the corporation which built the Merchants' Bridge across the Mississippi River at St. Louis. Seth Cobb was married to socialite Zoe Cynthian Desloge, daughter of Firmin Rene Desloge, founder of the Desloge Family in America, and had one daughter, Josephine. The Desloge family were the founders of Desloge, Missouri and the massive Desloge Consolidated Lead Company.
Cobb was elected as a Democrat to the Fifty-second, Fifty-third, and Fifty-fourth Congresses (March 4, 1891-March 3, 1897). He was not a candidate for renomination in 1896. He resumed the grain commission business in St. Louis. He served as vice president of the Louisiana Purchase Exposition at St. Louis in 1904. He died in St. Louis, Missouri, May 22, 1909. He was interred in Calvary Cemetery.