| Henry C. Allen | |
| Office: | 32nd Speaker of the Virginia House of Delegates |
| Term Start: | 1877 |
| Term End: | 1879 |
| Predecessor: | J. Marshall Hanger |
| Successor: | Benjamin W. Lacy |
| Office2: | Member of the Virginia House of Delegates from Shenandoah County |
| Term Start2: | December 1, 1875 |
| Term End2: | December 2, 1879 |
| Predecessor2: | Harrison Riddleberger |
| Alongside2: | Joseph B. Strayer, David S. Henkel |
| Successor2: | Joseph B. Strayer |
| Birth Date: | March 19, 1838 |
| Birth Place: | Beaver Dam, Botetourt County, Virginia, U.S. |
| Parents: | John J. Allen Mary Payne Allen |
| Relatives: | Robert Allen |
| Party: | Democratic |
| Alma Mater: | University of Virginia |
| Profession: | farmer, lawyer |
| Branch: | infantry |
| Serviceyears: | 1861-1862 |
| Battles: | Battle of Gettysburg |
Henry Clay Allen (March 19, 1838 – October 31, 1889) was a Virginia lawyer and politician. He represented Shenandoah County in the Virginia House of Delegates, and served as that body's Speaker from 1877 until 1879.
Henry C. Allen was a middle son born at Beaver Dam, Botetourt County, Virginia, to lawyer and former Congressman, then Judge John J. Allen. His uncle Robert Allen also was a Congressmen.
On January 24, 1867, he married Julia McKay Gatewood.
During the American Civil War, he, his brothers and cousins all enlisted in the Confederate States Army.
After the war, Allen returned to the Shenandoah Valley, where his grandfather had practiced law as well as served as a judge.
Voters elected him to represent Shenandoah County in the Virginia House of Delegates. When Democrat Grover Cleveland became President, Allen was the United States Attorney for the Western District of Virginia from 1885 until 1889.