Augustus Schoonmaker Jr. (March 2, 1828 – April 9, 1894) was an American lawyer and Democratic politician.
His parents were second cousins, sharing the same great-grandparents, Jan and Margaret Hornbeck Schoonmaker.
Schoonmaker was originally a teacher and superintendent of schools in Ulster County.
Afterwards he served on the New York Board of Civil Service Commissioners (1883–1887) and was an original appointee of President Grover Cleveland to the Interstate Commerce Commission, serving from 1887 to 1890.
He married Louise Cooper (1835-1910) and they are both buried in Wiltwyck Cemetery in Kingston.