Benjamin Platt Carpenter (May 14, 1837 – December 24, 1921) was an American lawyer and politician from New York and Montana.

Carpenter was District Attorney of Dutchess County from 1864 to 1869; a delegate to the New York State Constitutional Convention of 1867-68; a delegate to the 1868 and 1884 Republican National Conventions; a member of the New York State Senate (11th D.) in 1876 and 1877; and Judge of the Dutchess County Court from 1878 to 1882.

At the New York state election, 1882, he ran for Lieutenant Governor of New York on the Republican ticket with Charles J. Folger, but they were heavily defeated by Democrats Grover Cleveland and David B. Hill.

After a short tenure, he was removed from office by the new Democratic President, Grover Cleveland, but he stayed in Montana, and was a delegate to the Montana State Constitutional Convention of 1889.

On December 24, 1921, Carpenter died in Chula Vista, San Diego County, California.