Samuel Maclay (June 17, 1741 – October 5, 1811) was an American politician from Union County, Pennsylvania.
He was born in Lurgan Township in the Province of Pennsylvania at Maclay's Mill and served in the Revolutionary War.
He was elected to the United States Senate as a Democratic-Republican by the Pennsylvania legislature and began service in 1803.
Popular among Pennsylvanians, he was an infrequent Senate speaker but was frequently mentioned as his party's possible candidate for governor, but was passed over in favor of Simon Snyder.
Despite the eventual repeal of the Embargo Act, Madison secured Pennsylvania's support and Maclay realized that he was out of step with his fellow party members and Pennsylvanians.