Allen Carpenter Beach (October 9, 1825 – October 17, 1918) was an American lawyer and politician from New York.
He was born on October 9, 1825, in Fairfield, Herkimer County, New York, the son of Rev. Allen R. Beach (1797–1879) and Amy Brown Beach (1803–c.1890). He graduated from Union College in 1848, and was admitted to the bar in 1852. His first wife Abby A. Woodruff died in 1856. In 1862, he married Olivia H. Pickering, and they had one daughter, Amy.
He was a delegate to the 1860 and 1876 Democratic National Conventions.
As a Democrat, he was Lieutenant Governor of New York from 1869 to 1872, elected in 1868 and 1870.
He was Secretary of State of New York from 1878 to 1879, elected in 1877 and defeated for re-election in 1879.
He died on October 17, 1918, in Rochester, New York.