Hampshire County is a county located in the U.S. state of West Virginia. Its county seat is Romney, West Virginia's oldest town (1762). Hampshire County was created by the Virginia General Assembly on December 13, 1753, from parts of Frederick and Augusta counties (Virginia) and is the oldest county in the state of West Virginia. The county lies in both West Virginia's Eastern Panhandle and Potomac Highlands regions.

Although its creation was authorized in 1753, Hampshire County was not actually organized until 1757 because the area was not considered safe due to the outbreak of the French and Indian War (1754-1763). According to Samuel Kercheval's  A History of the Valley of Virginia, the county was named in honor of its several prize hogs. The story goes that Thomas Fairfax, 6th Lord Fairfax of Cameron, who owned the Royal Grant to the area, came upon some very large hogs in Winchester and asked where they had been raised. He was told that they were from the South Branch Potomac River Valley (now Hampshire County). He remarked that when a county was formed west of Frederick that he would name it in honor of the county Hampshire, England, famous for its very fat hogs.