The name Gwenyth is a Welsh feminine given name derived from the Welsh elements "gwen" meaning fair, white, or blessed, and "yth" meaning aspect or being. It is believed to have originated in the 6th century during the medieval period in Wales.

The earliest known use of the name Gwenyth can be traced back to a 6th-century Welsh princess named Gwenyth ferch Culvynawyd, who was the daughter of a powerful king in what is now northern Wales. This suggests that the name was in use among the Welsh nobility and royalty during this time.

In the 9th century, the name Gwenyth is mentioned in the Welsh legal text "Cyfnerth Laws" as one of the names given to daughters of the Welsh aristocracy. This further solidifies the name's long-standing association with Welsh culture and tradition.

One of the most notable historical figures bearing the name Gwenyth was Gwenyth Goch, a 14th-century Welsh warrior and rebel leader who fought against English rule in Wales. Her nickname "Goch" means "the Red" in Welsh, likely referring to her fiery hair or her fierce determination in battle.

In the 16th century, Gwenyth verch Ieuan ap Rhydderch, a Welsh noblewoman, was recorded as one of the last speakers of the Cumbric language, an ancient Celtic language once spoken in northern England and southern Scotland.

During the 17th century, Gwenyth Pugh, a Welsh Quaker and religious leader, was known for her efforts in promoting education and religious tolerance in Wales.

Another notable figure was Gwenyth Llewelyn, a 19th-century Welsh author and poet who wrote extensively about Welsh culture and the preservation of the Welsh language.

Throughout its long history, the name Gwenyth has maintained its strong connection to Welsh heritage and has been borne by various notable individuals in various fields, from warriors and rebel leaders to religious figures and writers.