Cassius M. Clay was the youngest son of Brutus Junius Clay and Anne Field Clay. Like his namesake, the younger Cassius attended Yale University, graduating in the class of 1866. He served in both houses of the Kentucky General Assembly in the 1870s and 1880s. He presided at the convention held in 1890 and 1891 which wrote a new state constitution. In 1891 he became a candidate for the Democratic nomination for governor, but was defeated in great measure by the railroad interest, and was again defeated for the nomination in 1895. In 1902 he was appointed a member of the Board of Trustees of the State University, a position he held until his death in 1913. Married to Mary Blythe Harris and Susan Elizabeth Clay.