Horatio Seymour (1813 Middlebury, Addison County, Vermont – September 1872) was an American lawyer and politician from New York.
He graduated from Middlebury College, studied law in Syracuse, New York, was admitted to the bar, and commenced practice in Buffalo, New York in 1836.
He married Elizabeth Staats (1816–1876), and they had two sons.
He was a member of the New York State Assembly (Erie Co., 2nd D.) in 1862 and 1863.
He was Surrogate of Erie County from 1868 until his death.