Rubellia Bassa (born between 33-38) was a daughter of Gaius Rubellius Blandus, consul in AD 18 and possibly his wife Julia Livia (killed 43) or an earlier wife.
It has been theorized that her mother was Julia Livia (daughter of Julius Caesar Drusus and Livilla), which would make Bassa the great-granddaughter of Tiberius; however, this lineage is uncertain because her father, Gaius Rubellius Blandus married Julia when he was around 55, which makes an earlier marriage likely (possibly to a Laecania Bassa), and Rubellia Bassa may have been the daughter of Blandus by this theorized earlier marriage.
Bassa had at least one sibling, a (?half)brother named Gaius Rubellius Plautus, who was one of the nearest heirs of the blood of Augustus (being the grandson of Drusus Caesar, who was an adopted grandson of Augustus). Plautus was forced to kill himself in 62 and his wife Antistia Pollitta and children were executed four years later (perhaps because the children were direct descendants of previous Roman Emperors.
Rubellia Bassa married Octavius Laenas, maternal uncle of the future emperor Nerva. Ronald Syme claims that Sergius Octavius Laenas Pontianus, consul in 131 under Emperor Hadrian, set up a dedication to his grandmother, "[Rub]elliae / [Bla]ndi f(iliae) Bassae / Octavi Laenatis / Sergius Octavius / Laenas Pontianus / aviae optimae ". This obscure link is perhaps a continuation of the Julio-Claudian bloodline through the 2nd century.