Horatio Wallace Knapp (March 31, 1869 – April 4, 1929) was an American politician who represented Clinton County in the New York State Assembly over the course of 1903, 1904, 1905 and 1906; and in the New York State Senate during 1907 and 1908.
Knapp was born in Mooers, New York. He was a merchant in Mooers, and later also engaged in banking, and electric power supply.
Knapp was Supervisor of the Town of Mooers for several terms beginning in 1899, and Chairman of the Board of Supervisors of Clinton County in 1901 and 1902.
He died, in St. Petersburg, Florida.