Harrison Gray Otis Blake (March 17, 1818 – April 16, 1876) was a U.S. Representative from Ohio. Born in Newfane, Vermont, Blake moved to Salem, New York, and in 1830 to Guilford, Ohio. He received his education at public schools, later studying medicine at Seville for one year. In 1836, he moved to Medina, where he engaged in mercantile pursuits and studied law. He was admitted to the bar and commenced practice in Medina. From 1846 to 1847, he served as a member of the Ohio House of Representatives, and was elected to the Ohio State Senate in 1848, serving as that chamber's president.