Mark of Cornwall was a king of Kernow

Kingdom of Cornwall

The Kingdom of Cornwall was an independent polity in southwest Britain during the Early Middle Ages, roughly coterminous with the modern English county of Cornwall. During the sub-Roman and early medieval periods Cornwall was evidently part of the kingdom of Dumnonia, which included most of the...

 (Cornwall

Cornwall

Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

) in the early 6th century. He is most famous for his appearance in Arthurian

King Arthur

King Arthur is a legendary British leader of the late 5th and early 6th centuries, who, according to Medieval histories and romances, led the defence of Britain against Saxon invaders in the early 6th century. The details of Arthur's story are mainly composed of folklore and literary invention, and...

 legend as the uncle of Tristan

Tristan

Tristan is one of the main characters of the Tristan and Iseult story, a Cornish hero and one of the Knights of the Round Table featuring in the Matter of Britain...

 and husband of Iseult

Iseult

Iseult is the name of several characters in the Arthurian story of Tristan and Iseult. The most prominent is Iseult of Ireland, wife of Mark of Cornwall and adulterous lover of Sir Tristan. Her mother, the Queen of Ireland, is also named Iseult...

, who engage in a secret affair.
Mark sent Tristan as his proxy to fetch his young bride, the Princess Iseult, from Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

. Tristan and Iseult

Tristan and Iseult

The legend of Tristan and Iseult is an influential romance and tragedy, retold in numerous sources with as many variations. The tragic story is of the adulterous love between the Cornish knight Tristan and the Irish princess Iseult...

 fall in love, and, with the help of a magic potion, proceed to have one of the stormiest love affairs in medieval literature

Medieval literature

Medieval literature is a broad subject, encompassing essentially all written works available in Europe and beyond during the Middle Ages . The literature of this time was composed of religious writings as well as secular works...

.