"Duke of Cornwall" appears as a title in pseudo-historical authors such as Geoffrey of Monmouth. The list is patchy and not every succession was unbroken. Indeed, Geoffrey repeatedly introduces Dukes of Cornwall only to promote them to the Kingship of the Britons and thus put an end to their line as (merely) dukes. As adjuncts or supporting roles to the kings of the Britons, the legendary dukes of Cornwall are considered part of the vast Matter of Britain, and can also be found in other stories, such as Culhwch and Olwen, the Prose Tristan, Havelok the Dane, and Gesta Herewardi. Antiquaries such as Richard Carew (Survey of Cornwall, 1602) and John Williams (the Book of Baglan, 1600–1607) also provide lists of legendary rulers of Cornwall, often combining the above with other sources.
As a result, these lists are more often thought of as a conglomeration of various Celtic rulers, Celtic warlords, and mythical heroes. If the lists of kings of Britain are legendary, then the list of dukes must be considered still more a genealogical and historical legend with no solid basis in the view of most historians. The titles given for the rulers also vary, even within sources; Geoffrey's History, has the title fluctuating between "duke" (dux Cornubiae) and "king" (rex Cornubiae), and Carew wrote that before the Norman Conquest "these titles of honour carry a kinde of confusednes, and rather betokened a successive office, then an established dignity. The following ages received a more distinct forme, and left us a certeyner notice."
Pre-Arthurian NameTitleNotesApproximate time frameSourcesCorineusDukeFirst ruler of Cornwall; given the land by Brutus1154 BCHistoria Regum Britanniae; Survey of CornwallGwendolenQueenDaughter of Corineus; became queen regnant of BritainHistoria Regum BritanniaeGorbonianDukeSon of Camber; also became chief governor of CambriaBook of Baglan folios 84, 305Difnwall HenDukeSon of Gorbonian; also one of or the chief governor of CambriaBook of Baglan folios 84, 306KingenDukeSon of Difnwall Hen; also chief governor of CambriaBook of Baglan folios 84, 306AserDukeSon of Kingen; also chief governor of CambriaBook of Baglan folios 84, 306BledhudDukeSon of Aser; also chief governor of CambriaBook of Baglan folios 84, 306HenwinDukeSon of Bledhud; also chief governor of Cambria; Duke under King Leir; husband of Leir's daughter Regan or Gonorille, and with her ruled half of Britain899 BCHistoria Regum Britanniae; Survey of Cornwall; Book of Baglan folios 84, 306CunedagiusDukeSon of Henwin; duke of Cornwall under Queen Cordelia; became king of Britain; built a temple to Apollo in Cornwall832 BCHistoria Regum Britanniae; Survey of CornwallAntoniusDukeGreat-great-grandson of Henwin; second son of Gorwst, king of BritainBook of Baglan folios 83, 306AedhmawrDukeSon of AntoniusBook of Baglan folios 83, 306, 307PrydanDukeSon of AedhmawrBook of Baglan folios 83, 307KynfarchDukeSon of PrydanBook of Baglan folios 83, 307ClotenKing/Duke/PrinceSon of Kynfarch; ruled Cornwall during the pentarchy after Ferrex and Porrex528 BCHistoria Regum Britanniae; Survey of Cornwall; Book of Baglan folios 83, 165, 307; GorboducDyfnwal MoelmudKing/DukeSon of Cloten; unites Britain as its kingHistoria Regum Britanniae; Survey of Cornwall; Book of Baglan folios 83, 165, 307BelinusSon of Dyfnwal Moelmud; became king of Britain, and direct ruler of Loegria, Kambria, and Cornwall, as his appanage; brother of Brennus430 BCHistoria Regum Britanniae; Survey of CornwallTasciovanusDukeSon of King Lud; made duke by his uncle King Cassibelanus; succeeds him as king of Britain96 BCHistoria Regum Britanniae; Survey of CornwallThanorKingContemporary with Joseph of Arimatheac. 1st century ADProse TristanAsclepiodotusDukeDuke under Allectus; becomes king of Britain231 ADHistoria Regum Britanniae; Survey of CornwallConan MeriadocDukeNephew of Octavius; became king of Armorica329 ADSurvey of CornwallSalomonDukeFather of Corinius who was said to have attended the Synod of Arles351 ADSurvey of Cornwall
Arthurian Sources diverge leading up to the time of King Arthur, with Caradoc placed either during the time of Arthur (as in the Welsh Triads, and later tradition), soon before Gorlois (Carew's Survey of Cornwall), or before his brother Dionotus as Caradocus in the Historia Regum Britanniae, while the Book of Baglan only keeps Gorlois, but gives him an entirely different set of ancestors. Gorlois is sometimes given other names, such as Ricca in Culhwch and Olwen, Tador in William Worcester's Itineraries, and Hoel in the Prose Merlin. In some sources Gorlois is not ruler of Cornwall, and is replaced in this role by Mark in the Prose Tristan, Ydiers in the Prose Merlin, and the unnamed King Cornwall in "King Arthur and King Cornwall".
Welsh Triads NameTitleNotesApproximate time frameSourcesArthurChief lordChief lord of the "three tribal thrones of the Island of Prydain": Celliwig in Cornwall, Pen Rhionydd in the north, and Mynyw in WalesPeniarth MS 54, triad 1Caradawg VreichvrasChief elderArthur's chief elder for Cornwall; also one of the "three cavaliers of battle of the Island of Prydain"Peniarth MS 54, triads 1, 16
Historia Regum Britanniae NameTitleNotesApproximate time frameSourcesCaradocusDuke/KingDuke under King Octavius; put forward Maximianus as king of Britain and was king of Cornwall under himHistoria Regum BritanniaeDionotusKingBrother of Caradocus; made regent of Britain during Maximianus' campaignsHistoria Regum BritanniaeGorloisDukeDuke under kings Aurelius Ambrosius and Uther; first husband of Igraine, Arthur's motherHistoria Regum BritanniaeCadorDuke/KingRuler of Cornwall as one of four kings under King ArthurHistoria Regum BritanniaeConstantineSon of Cador; kinsman of King Arthur, who he succeeds as king of Britain542 ADHistoria Regum Britanniae
Survey of Cornwall NameTitleNotesApproximate time frameSourcesDionethusDuke/KingSent Saint Ursula and 11,000 handmaids to Conan Meridock in Armorica; also called Dionotus383 ADSurvey of CornwallMoigneDukeBrother of Aurelius and Uter-Pendragon; governor of the realm under Emperor Honorius433 ADSurvey of CornwallCarodocDukeTasked by Octavius to found the University of Cambridge443 ADSurvey of CornwallGorloisDukeHusband of Igerna with whom Uter-Pendragon had Arthur and Amy500 ADSurvey of CornwallCadorEarlKilled King Childerick of the Saxons who invaded after being banished by Arthur526 ADSurvey of CornwallMarkeKingIn the time of ArthurSurvey of Cornwall
Book of Baglan NameTitleNotesApproximate time frameSourcesOwenDukeDirect descendant of Dyfnwall Moelmud; son of Maxentius, king of Britain and emperor of RomeBook of Baglan folios 82, 276, 309MoureDukeSon of Owen; also called Mour or MoorBook of Baglan folios 82, 276, 309GolorDukeSon of Moure; also called SolorBook of Baglan folios 82, 276, 309Pendoff the GreatDukeSon of Golor; also duke of Wessex; also called Pendof or Pendaff the GreatBook of Baglan folios 81, 276, 309SortogusDukeSon of PendoffBook of Baglan folios 81, 276, 309GurleisDuke/PrinceSon of Sortogus; married Eigyr, a descendant of Joseph of Arimathea's sister; also called Goulisor or GwrleisBook of Baglan folios 81, 276, 309CadorDuke/PrinceSon of GurleisBook of Baglan folios 81, 276
Culhwch and Olwen NameTitleNotesApproximate time frameSourcesArthurHas his court at Celliwig in Cornwallc. 6th century ADCulhwch and OlwenRiccaChief ElderFather of Arthur's half-brother Gormantc. 6th century ADCulhwch and OlwenGwyn HywarOverseerOverseer or steward of Cornwall and Devon; one of the nine who plotted the Battle of Camlannc. 6th century ADCulhwch and Olwen
William Worcester's Itineraries NameTitleNotesApproximate time frameSourcesTadorDukeHusband of Arthur's mother; killed at Castle an DinasWilliam Worcester's Itineraries, 1478, Castle an Dinas
Prose Tristan NameTitleNotesApproximate time frameSourcesFelixKingMany generations after Thanorc. late 5th century ADProse TristanMark of CornwallKingSon of Felix, and uncle of Tristanc. early 6th century ADProse Tristan
"King Arthur and King Cornwall" NameTitleNotesApproximate time frameSourcesKing CornwallKingUnnamed magician-king of Cornwall; fathered a daughter with Guinevere; beheaded by King Arthur"King Arthur and King Cornwall"
Prose Merlin NameTitleNotesApproximate time frameSourcesHoelDukeDuke of Tintagel, husband of Ygerne; had five daughters with her, who married King Lot, King Ventres, King Urien, and King BriadasProse MerlinYdiersKingKing of Cornwall; one of seven kings who fight Arthur; joins forces with Arthur during the Saxon invasionProse Merlin
Post-Arthurian Historia Regum Britanniae NameTitleNotesApproximate time frameSourcesBledericDukeDuke at the time Augustine arrives; dies leading the Britons in war against the Saxon King Ethelfrid of Northumbria597 ADHistoria Regum Britanniae
Survey of Cornwall NameTitleNotesApproximate time frameSourcesBledericDukeFought with other Welsh kings against Ethelferd, and by dying won the battle603 ADSurvey of CornwallIvorSon of King Alane of Brittany; won Cornwall, Devon, and Somerset from the Saxons688 ADSurvey of CornwallRodericKingKing of the Bretons in Wales and Cornwall; lost Cornwall to King Adelred of Wessex and fled to Wales720 ADSurvey of CornwallBletiusPrincePrince of Cornwall and Devon under King Roderic720 ADSurvey of CornwallDungarthKingDrowned by mischance872 ADSurvey of CornwallAlpsiusDukeDuke of Devon and Cornwall900 ADSurvey of CornwallOrgeriusDukeFather of Alfride who married King Edgar959 ADSurvey of CornwallCondorEarlPaid homage to William the Conqueror for his earldom1067 ADSurvey of Cornwall
Book of Baglan NameTitleNotesApproximate time frameSourcesBredriceDukeGrandson of Cador; son of Constantyn III the king of Britain; also called PeledricBook of Baglan folios 81, 276ClementDuke/PrinceSon of Bredrice; also called ClemeasBook of Baglan folios 81, 276PedrockDukeSon of Clement; also called PedronckBook of Baglan folios 81, 276ProgmaellDukeSon of PedrockBook of Baglan folios 81, 276CoilbyeDukeSon of Progmaell; also called KoilbieBook of Baglan folios 81, 276CaretDukeSon of Coilbye; also called GaretBook of Baglan folios 81, 276DwnDukeSon of CaretBook of Baglan folios 81, 276IthelDukeSon of Dwn; also called IthynBook of Baglan folios 81, 276DyfnuallDukeSon of Ithel; also called BoifunallBook of Baglan folios 81, 276CanordolyeDukeSon of Dyfnuall; also called CanordolyBook of Baglan folios 81, 276OstwalltDukeSon of Canordolye; also called UstwalldBook of Baglan folios 81, 276HernamDukeSon of OstwalltBook of Baglan folios 81, 276HopkinDukeSon of Hernam; also called HopkynBook of Baglan folios 81, 276MordaphDukeSon of Hopkin; also called MordaffBook of Baglan folios 81, 276FferverdynDukeSon of MordaphBook of Baglan folios 81, 276ElnydDukeSon of FferverdynBook of Baglan folios 81, 276AlanorDukeSon of ElnydBook of Baglan folios 81, 276RolopedaphDukeSon of AlanorBook of Baglan folios 81, 276VortegynDukeSon of Rolopedaph; also duke of WessexBook of Baglan folios 81, 276VephyneDukeSon of Vortegyn; also duke of WessexBook of Baglan folios 81, 276AluredDukeSon of Vephyne; also duke of WessexBook of Baglan folios 81, 276GodwynDukeSon of Alured; also duke of WessexDied 1013Book of Baglan folios 39, 81, 276, 327, 373HerbertLord/EarlSon of Godwyn; also duke of Wessex; father of Henry Herbert Lord of the Forest of Deane and Chamberlain to Henry I of EnglandBook of Baglan folios xxiii, xxiv, 39, 81CandorEarlPaid homage to William the ConquerorEarl in 1066Book of Baglan folio 196CandorEarlSon of Candor; father of Avicia who married Reginald de Dunstanville, 1st Earl of CornwallBook of Baglan folio 196
Havelok the Dane NameTitleNotesApproximate time frameSourcesGodrichEarlEarl under King Athelwold; made regent of Englandc. 6th/7th century ADHavelok the DaneBertramEarlGodrich's cook; made earl by Havelokc. late 6th/7th century ADHavelok the Dane
Gesta Herewardi