Fannia (fl. around 100 AD) was a woman of Ancient Rome, notable as the granddaughter of Arria Major.
Fannia is recorded in the writings of Pliny the Younger as a woman of fortitude and respectability. As with her grandmother, Fannia is described as a political rebel in her own right. She was married to Helvidius Priscus and followed him twice into exile, once when he was exiled by Nero for sympathising with two outcasts (Brutus and Cassius), then for the second time when he was exiled by Vespasian for opposing his reign.
Eventually, Fannia herself was exiled in 93 AD for instigating the creation and publication of a biographical book about her husband under the rule of Domitian. This mild sentence was reflected in the death of the author, Herennius Senecio, who was executed due to his involvement. During the trial of Senecio, he blamed the book on Fannia as she had asked him to write it, a statement that Fannia confirmed. She was asked if, and confirmed that, she had given Senecio her husband's diaries. Pliny writes that: "she did not utter a single word to reduce the danger to herself." When her possessions were seized, Fannia managed to save the diaries and biography of her husband and even took them with her into exile.
In 103 AD, Pliny recorded that Fannia had "contracted this illness". She had been nursing a relative (Junia) from an unnamed "serious illness" and as Junia was a vestal virgin she had been obliged to leave Vesta's hearth and go into the care of a matron. Whilst taking care of her Fannia herself fell ill, and is described by Pliny: thus: "She has constant fever and a cough that is getting worse; she is emaciated and generally in decline. Only her spirit is vigorous, worthy of her husband." Though Pliny the Younger was regularly prone to exaggeration of great extent, his repeated expressions of worry suggest that the illness was one from which Fannia did not recover.