The name Gwendolyn has its roots in the ancient Celtic language of Brittonic. It is derived from the Welsh elements "gwen" meaning fair or blessed, and "dyl" meaning ring or circle. The name can be interpreted to mean "ring of blessing" or "fair circle."

Gwendolyn likely originated in the British Isles, particularly in Wales and Cornwall, during the early medieval period. It was a popular name among the Welsh and Cornish nobility and royalty. Similar spellings found in historical records include Gwendolen, Gwendoline, and Gwyndolen.

One of the earliest known references to the name Gwendolyn can be found in the Welsh tale of "Culhwch and Olwen" from the Mabinogion, a collection of medieval Welsh folklore and mythology. In this tale, Gwendolyn is mentioned as the daughter of a powerful king.

The name gained wider popularity during the Middle Ages and was used by several notable historical figures. Gwendolyn Fitzalan, born around 1285, was a Welsh noblewoman and the wife of Sir Robert de Mortimer. Gwendolyn Stradling, born in the 15th century, was a Welsh heiress and landowner.

In the literary world, Gwendolyn appears as a character in Edmund Spenser's epic poem "The Faerie Queene," published in 1590. This helped to further popularize the name in England and other parts of Europe.

Another famous bearer of the name was Gwendolyn Brooks (1917-2000), an American poet and teacher who became the first African American to win the Pulitzer Prize for Poetry in 1950. She was a prominent figure in the Black Arts Movement and was also appointed as the Poet Laureate of Illinois.

Gwendolyn Christie (born 1978) is a British actress known for her role as Brienne of Tarth in the HBO series "Game of Thrones." She has also appeared in various films, including "Star Wars: The Force Awakens" and "Star Wars: The Last Jedi."