Edward Allen Hannegan (June 25, 1807 - February 25, 1859) was a United States Representative and Senator from Indiana. Born in Hamilton County, Ohio, he moved with his parents to Bourbon County, Kentucky the same year. He attended the public schools, studied law, taught school and worked as a farm hand; he was admitted to the bar in 1827. He moved to Indiana and, after residencies in Vincennes and Terre Haute, settled in Covington, where he commenced the practice of law; in 1832-1833 and 1841-1842 he was a member of the Indiana House of Representatives. He elected as a Democrat to the Twenty-third and Twenty-fourth Congresses, serving from March 4, 1833-March 3, 1837.
Hannegan was not a candidate for renomination in 1836 and resumed the practice of law; he was elected as a Democrat to the U.S. Senate in 1842 and served from March 4, 1843, to March 3, 1849. He was an unsuccessful candidate for renomination in 1848. While in the Senate he was chairman of the Committee on Private Land Claims (Twenty-ninth Congress) and a member of the Committee on Roads and Canals (Twenty-ninth and Thirtieth Congresses) and the Committee on Foreign Relations (Thirtieth Congress). He was United States Minister to Prussia in 1849-1850 and resumed the practice of law in Covington. In 1857 he moved to St. Louis, Missouri in 1857, where he continued to practice law until his death by overdose of morphine in 1859; interment was in Woodlawn Cemetery, Terre Haute, Indiana.