Yup, there really is one. St. Brienna (aka Bryene, Bruene, Brienne, or Briena) of Sivapolis or Sibapolis, was the elderly abbess (and aunt) of the martyr St. Febronia of Nisibis. St. Brienna’s teacher and abbess had been a deaconess named Platonia or Platonis. “It had been Platonia’s practice not to let the sisters do any work at all on Fridays; instead they used to gather in the place for prayer and celebrate the Office of Matins. Then, from dawn to the third hour (9 A.M.) Platonia used to take a book and read to them. After the Office of the Third Hour she would give the book to Bryene and tell her to read to the sisters until vespers. When Bryene took over as head of the convent, she continued this practice.”
Unfortunately, St. Brienna was of advanced age when persecution came, and had to be carried wherever she went. After the nuns received a warning, she sent away all her nuns to safety, if they wished to go. But St. Febronia was too sick to go. St. Brienna and another elderly nun and teacher, Bl. Thomais, stayed with her. St. Febronia was captured, but St. Brienna was spared to reorganize the scared nuns who returned, and Thomais was able to go in disguise to see St. Febronia’s end. Old St. Brienna didn’t die until two years later, on the anniversary of St. Febronia’s birth into glory. She was succeeded by Bl. Thomais.
We don’t have a court transcript version of events, as we do with many Roman martyrs. There’s a story version of the Acts of St. Febronia that’s supposed to be by her fellow nun Thomais, but apparently this was a sort of Christian historical fiction piece. However, the concern with the rule that the nuns lived under, and the teachers from whom they got it, suggests to many that the actual author really was a nun from St. Febronia’s in later days.
Anyway, St. Febronia is very popular in the Eastern churches and rites, and she’s also got a statue in St. Peter’s Square. So St. Brienna is a fairly well-known lady, and her name’s got a long heritage as a baptismal or Christian name.
This webpage translates the Acts of St. Febronia. Tons of interesting stuff!
The same listing also notes another St. Briena — Briena Securae, from Spain/Hispania. Ven. Cesario Baronius’ edition of the Roman Martyrology apparently talks about her in the listing under St. Thecla for September 23, but I haven’t found that one. However, page 158 of Paradisi Carmeliti Decoris, by Alegre, talks about St. Briena having come to Spain to establish a monastery in the Tarraconensis province.
So if your name is Briana, Brianna, Briena, Brienna, or Brienne, you have a very old baptismal name and a very neat patron saint!