Vortiporius or Vortipor (Old Welsh: Guortepir, Middle Welsh Gwrdeber or Gwerthefyr) was a king of Dyfed in the early to mid-6th century. He ruled over an area approximately corresponding to the modern Pembrokeshire. Records of this era are scant, and virtually nothing is known of him or his kingdom. The only contemporary information about the person comes from Gildas, in a highly allegorical condemnation from his De Excidio et Conquestu Britanniae (English: On the Ruin and Conquest of Britain). At the time the work was written (c. 540), Gildas says that he was king of Dyfed, that he was grey with age, that his wife had died, and that he had at least one daughter.
As a legendary king in Geoffrey of Monmouth's treatment of the Matter of Britain, the Historia Regum Britanniae, he was the successor of Aurelius Conanus and was succeeded by Malgo. He is not mentioned in the Historia Brittonum attributed to Nennius. Vortiporius appears in the Irish genealogy given in the 8th century work, The Expulsion of the Déisi, with his name given as Gartbuir. The pedigree given in the Harleian MS. 5389 (written c. 1100) is nearly identical, with his name given as Guortepir. In the Jesus College MS. 20 he is Gwrdeber. The genealogy in Expulsion says he was a descendant of Eochaid Allmuir (English: Eochaid the Foreigner [literally (from) Overseas]), who is said to have led a sept of the Déisi in their settlement of Dyfed c. 270.
A memorial stone was discovered in 1895 near the church of Castell Dwyran in Carmarthenshire bearing a Christian cross and with inscriptions in both Latin and in ogham. Dedicated to Voteporigis in the Latin inscription and Votegorigas in ogham, it was immediately assumed that this referred to Vortiporius. However, the assumption is refuted by modern linguistic analysis, which notes that the missing 'r' in the first syllable of 'Voteporigis'/'Votegorigas' is significant, and so the stone must be dedicated to a different person.