Gorlois (Gwyrlys) Sap ap Sardog Duke of Cornwall 
- Born: Abt 460, Din-Tagell or Tintagel Castle, Cornwall, Bri
- Marriage: Eigr or Ygerna verch Amlawdd Duchess of Cornwall , High Queen of Britain 
- Died: 475, Britain about age 15
Gorlois (Gwrlais in Welsh) may have been a governor of Cerniw (Cornwall), the western portio n of Dumnonia, under King Erbin. His historicity is confirmed by the evidence of place-names such as Carhurles (Caer-Wrlais) and Treworlas (Tre-Wrlais). Late pedigrees, attributed to Iolo Goch, suggest he was a descendant of Gerdan, a younger son of King Solor of Cernyw (Glywysing). It may either be through coincidence or confusion that Gorlois' ancestry stems from Cernyw (Glywysing), while he lived in Cerniw (Cornwall).
Title: Ordinance Index (R) Author: The Church of Jesus Christ of Latter-day Saints Publicatio n: 1993 02 28 Edition
Title: Early British Kingdoms: Geneaologies: Mid-South Welsh Royal Pedegree: Glywysing, Gwynl lwg, Penychen, Edeligion & Gorfyny Author: David Nash Ford Publication: 2000, www.earlybritishkingdoms.com/gene\\finddu.html
Gorlois married Eigr or Ygerna verch Amlawdd Duchess of Cornwall , High Queen of Britain  [MRIN: 551617584], daughter of Amlawdd (Wledig) of Wales ap Cynwal  and Gwen verch Cunedda of Wales . (Eigr or Ygerna verch Amlawdd Duchess of Cornwall , High Queen of Britain  was born in 454 in Dumonia, Britain and died in Caerlaveroc, Solwayfirth, Dumfries, Scotland.)