Henry De Lamar Clayton (February 10, 1857-December 21, 1929) was an American politician from Alabama.
Henry D. Clayton was born in Clayton, Alabama and received his undergraduate degree and law degree from the University of Alabama. Clayton was elected as a Democrat in Alabama House of Representatives from 1890 to 1891. From there, he went on to serve as U.S. Attorney for the Middle District of Alabama, then in the House of Representatives 1897 to 1914 where he authored the Clayton Antitrust Act. He served as a delegate from his home state to the 1912 Democratic National Convention. He then went on to serve in a variety of positions for the Federal Court System and was at one point appointed to fill the U.S. Senate vacancy left by the death of Joseph F. Johnston, but due to controversy, his name was withdrawn.
He died in Montgomery, Alabama and is buried in Eufaula, Alabama.
His brother, Bertram Tracy Clayton, was also a member of the House of Representatives.