Cassius Marcellus Clay, American journalist, lawyer, and diplomat, United States Ambassador to Russia (d. 1903)
Cassius Marcellus Clay (October 19, 1810 – July 22, 1903), nicknamed the "Lion of White Hall", was a Kentucky planter, politician and emancipationist who worked for the abolition of slavery. A founding member of the Republican Party in Kentucky, he was appointed by President Abraham Lincoln as the U.S. minister to Russia. Clay is credited with gaining Russian support for the Union during the American Civil War.