Fregenal de la Sierra (originally Frexnal or Frexenal) is a municipality located in the province of Badajoz, Extremadura, Spain.

Today major industries include cork extraction and the processing of pork from Iberian pigs.

In the vicinity of the present town lie the ruins (almost entirely buried and little-researched) of a Celtic fort called Nertóbriga, which became known as Nertóbriga-Concordia Iulia after the Roman conquest.

The only reference made by Christians about this city is the name Castillo de Valera, which was dated by the Knights Templar.

The city was conquered by Fernando III with the help of the Templars, but first appearance of Fregenal in historical records was in 1283 when the population was given by Alfonso X of Castile to the Order of the Temple for its work in the reconquista.