Wilmon Whilldin Blackmar was a United States military officer who fought with the Union Army as a member of the 15th Pennsylvania Cavalry and the 1st West Virginia Cavalry during the American Civil War. He received his country's highest award for bravery during combat, the U.S. Medal of Honor, for his "extraordinary heroism" for taking the initiative, during a critical stage of the Battle of Five Forks on April 1, 1865, to lead a successful advance upon the enemy while fighting with the 1st West Virginia Cavalry. His award was conferred on October 23, 1897.

The 1st West Virginia Cavalry Regiment served in the Union Army during the American Civil War. Although it started slowly, it became one of the most active and effective of the West Virginia Civil War regiments—and had 14 Medal of Honor recipients, the most for any West Virginia regiment during the war. It was originally called the 1st Virginia Cavalry, not to be confused with the Confederate 1st Virginia Cavalry. Some reports added "Union," "Loyal" or "West" when identifying this regiment. After the Unionist state of West Virginia was officially admitted to the Union in 1863, the regiment became the 1st West Virginia Cavalry Regiment. The National Park Service identifies it as the 1st Regiment, West Virginia Cavalry.