Roman family within the gens Calpurnii.
Lucius Calpurnius Piso Frugi (2nd century BCE), as plebeian tribune, pushed through a law ensuring judicial review of provincial administration by senators, to prevent cirruption and expolitation of provinces. He was also a political opponent of Tiberius Gracchus. His comprehensive history of Rome from its foundation to his own times is, alas, only fragmentarily preserved.
Lucius Calpurnius Piso Caesoninus (c. 101 BCE - c. 42 BCE), father-in-law to Caius Julius Caesar, was consul in 58 BCE and Marcus Tullius Cicero's sworn enemy. In the chaos and civil war following Caesar's assassination, he tried to broker a deal between the warring parties, but failed.
Gnaeus Calpurnius Piso (died 20) was in 17 sent to Syria as procurator for Emperor Tiberius, while Germanicus had supreme command of the eastern provinces. Open enmity between the two led to accusations against Piso, after Germanicus' death, of having poisoned him, and for malfeasance in office. Piso evaded the issue in the classic Roman fashion - by committing suicide.
Caius Calpurnius Piso (died 65) gave his name to the Pisonian conspiracy against Emperor Nero in 65. He committed suicide when the conspiracy was uncovered.