The given name Rhaena has its origins in the ancient Valyrian language of the fictional world of Westeros, created by author George R.R. Martin in his A Song of Ice and Fire book series. The name is derived from the Valyrian word "rhaenys," which means "queen" or "princess."

In Martin's fantasy universe, Rhaena was the name of several princesses of the Targaryen dynasty, a powerful family of dragonriders and rulers of the Seven Kingdoms. The first known Rhaena Targaryen lived during the reign of King Jaehaerys I in the late 1st century AC (After Conquest). She was the daughter of Prince Aemon Targaryen and Lady Jocelyn Baratheon.

Another notable Rhaena Targaryen was the daughter of Prince Daemon Targaryen and Lady Laena Velaryon, born in 97 AC. She was a dragonrider and played a role in the Targaryen civil war known as the Dance of the Dragons. Rhaena and her dragon, Morning, participated in the Battle of Rook's Rest in 129 AC.

A third Rhaena Targaryen lived during the reign of King Viserys II in the late 2nd century AC. She was the daughter of Prince Aegon and Princess Rhaena Targaryen. This Rhaena was known as Rhaena of Pentos, as she spent many years in exile in the Free City of Pentos.

Outside of Martin's fictional world, the name Rhaena has not been widely used historically. However, it has gained popularity among fans of the A Song of Ice and Fire book series and the Game of Thrones television adaptation. Some fans have chosen to name their children Rhaena as a tribute to the Targaryen princesses.

While the name Rhaena is not found in ancient texts or historical records, its Valyrian roots and association with the powerful Targaryen dynasty have made it a popular choice among fans of fantasy literature and the Game of Thrones universe.