NERVA is also an acronym for Nuclear Engine for Rocket Vehicle Application, part of a NASA project to produce a nuclear thermal rocket engine.

Marcus Cocceius Nerva (November 8, 35 AD - January 27 98), Roman emperor (AD 96 - 98), was a member of the Italian nobility rather than one of the elite of Rome; in this he was like Vespasian, the founder of the Flavian dynasty. He was born in the Etruscan town of Narnia, to the north of Rome. He was the last emperor who was Italian both by family and by birth. Nerva had not pursued the usual administrative career, although he had been consul with Vespasian in 71 and with Domitian in 90.

After Domitian's assassination in 96 following his reign of terror, Nerva was elevated to emperor on September 18, 96. He may have been approached by the conspirators against Domitian because he was elderly (61) and childless.

After his accession, Nerva proceeded to set a new tone: he released those imprisoned for treason, banned future prosecutions for treason, restored much confiscated property, and involved the Senate in his rule. He probably did so as a means to remain relatively popular (and therefore alive), but this did not completely aid him. Support for Domitian in the army remained strong, and in October 97 the Praetorian Guard laid siege to the Imperial Palace on the Palatine Hill and took Nerva hostage. Nerva submitted to their demands, agreeing to hand over those responsible for Domitian's death and even giving a speech thanking the rebellious praetorians. Nerva then adopted Trajan, a commander of the armies on the German frontier, as his successor shortly thereafter in order to bolster his own rule. Casperius Aelianus , the Guard Prefect responsible for the mutiny against Nerva, was later executed under Trajan.