| Alexander Harper | |
| State: | Ohio |
| Term Start: | March 4, 1837 |
| Term End: | March 3, 1839 |
| Preceded: | Elias Howell |
| Succeeded: | Jonathan Taylor |
| Term Start2: | March 4, 1843 |
| Term End2: | March 3, 1847 |
| Succeeded2: | Nathan Evans |
| Term Start3: | March 4, 1851 |
| Term End3: | March 3, 1853 |
| Preceded3: | Nathan Evans |
| Succeeded3: | Harvey H. Johnson |
| Office4: | Member of the Ohio House of Representatives from Muskingum County |
| Term Start4: | 1820 |
| Term End4: | 1822 |
| Preceded4: | Robert McConnell John Reynolds |
| Succeeded4: | Nathan C. Findlay William H. Moore |
| Party: | Whig |
| Birth Date: | 5 February 1786 |
| Birth Place: | Belfast, Kingdom of Ireland |
| Death Place: | Zanesville, Ohio, US |
| Restingplace: | Greenwood Cemetery |
Alexander Harper (February 5, 1786December 1, 1860) was a U.S. Representative from Ohio for three different non-consecutive tenures in the mid-19th century.
Born near Belfast in the Kingdom of Ireland, Harper immigrated to the United States and settled in Zanesville, Ohio. He pursued preparatory studies, studied law, was admitted to the bar in 1813, and commenced practice in Zanesville. He served as member of the Ohio House of Representatives in 1820 and 1821. He served as president judge of the Court of Common Pleas 1822–1836.
Harper was elected as a Whig to the Twenty-fifth Congress (March 4, 1837 – March 3, 1839). He was later elected to the Twenty-eighth and Twenty-ninth Congresses (March 4, 1843 – March 3, 1847). He served as chairman of the Committee on Expenditures in the Post Office Department (Twenty-eighth Congress), and was on the Committee on Patents (Twenty-eighth Congress).
Harper was again elected to the Thirty-second Congress (March 4, 1851 – March 3, 1853). He resumed the practice of law.
He died in Zanesville on December 1, 1860, and was interred in Greenwood Cemetery.