The original Irish name for the area, Sliabh Beatha, has been anglicized as Slieve Beagh or half-anglicized Sliabh Beagh. According to Irish mythology, the name refers to the mythological figure Bith, who was buried in a cairn on top of the mountain. Although the summit is in fact marked by a cairn, called Doocarn, it is likely that the name's original meaning is mountain of birch. In County Monaghan, the locals typically refer to the Slieve Beagh as the Bragan Mountains, taking the name from a townland within the Slieve Beagh.