The given name Rhys originates from the Welsh language and has its roots in the ancient Celtic culture. It is believed to have derived from the Welsh word "rhys," meaning "ardor" or "enthusiasm." The name has been in use since the Middle Ages in Wales and surrounding regions.

One of the earliest recorded instances of the name Rhys can be found in the Welsh Triads, a collection of traditional folk tales and historical records dating back to the 13th century. These triads mention several Welsh princes and noblemen bearing the name Rhys, indicating its widespread use among the Welsh nobility during that time.

In the 12th century, Rhys ap Gruffydd, also known as The Lord Rhys, was a prominent Welsh prince and leader who played a significant role in the resistance against Norman rule in Wales. He was celebrated for his military prowess and his efforts to preserve Welsh independence.

Another notable figure in history was Rhys Goch Eryri, a 14th-century Welsh poet and warrior who is renowned for his patriotic and satirical poems. His works were widely circulated and helped to maintain the Welsh literary tradition during a period of English domination.

In the realm of religion, Rhys Prichard, a 16th-century Welsh clergyman and translator, made significant contributions by translating parts of the Bible and other religious texts into the Welsh language, making them accessible to the common people.

During the Tudor period, Sir Rhys ap Thomas was a prominent Welsh landowner and soldier who fought alongside Henry VII at the Battle of Bosworth Field in 1485. His support for the Lancastrian cause played a crucial role in Henry's ascension to the English throne.

Over the centuries, the name Rhys has been borne by numerous individuals across various fields, including literature, politics, and the arts. Some other notable figures include Rhys Davies, a 20th-century Welsh writer known for his short stories and novels depicting working-class life in Wales, and Rhys Ifans, a contemporary Welsh actor known for his roles in films such as Notting Hill and The Amazing Spider-Man.