The name Guinevere has its origins in the ancient Celtic language of Brittonic, spoken in what is now Great Britain during the 6th century AD. It is derived from the elements "ven" meaning fair or white, and "guern" meaning smooth or round, suggesting the name may have originally described a fair-skinned or beautiful woman. The spelling has evolved from earlier forms like Gwenhwyvar and Guanhumara.

Guinevere is most famously associated with the legendary Queen Guinevere, the wife of King Arthur in the mythical tales of Camelot and the Knights of the Round Table. These stories first appeared in written form in the histories of Geoffrey of Monmouth in the 12th century, drawing on much older Celtic folklore. Guinevere's famous affair with Arthur's knight Lancelot became a central part of the Arthurian romance tradition.

One of the earliest recorded instances of the name was Gwenhwyar, wife of a 6th century British king named Chenedig. Her grave is marked with an inscribed stone found near Catterick in Yorkshire, England, dating to around 580 AD. Another early bearer was Guanhamara, described as the wife of King Idernat in the 7th century Breton hagiography Vita Samsonis.

The name saw a resurgence in popularity during the Victorian era fascination with Arthurian legends. Notable Guineveres include the British writer Guinevere Duffield (1874-1962), American socialite Guinevere Porter-Palmer (1888-1965), and Guinevere Estill (1909-1992), a prominent American soprano singer and opera director.

Other famous Guineveres are the French medieval historian Guinevere Paleologina (1281-1342), one of the first European female scholars, and Lady Guinevere Petrie (1865-1918), an influential English archaeologist and Egyptologist who worked alongside her husband Sir Flinders Petrie.