Marcus Calpurnius Bibulus

Marcus Calpurnius Bibulus (died 48 BC) was a politician of the late Roman Republic.

Bibulus was the son in law of Marcus Porcius Cato Uticencis. In 59 BC he was elected consul, supported by the optimates, conservative republicans in the Senate and opponents of Julius Caesar's triumvirate. In this, Caesar, also elected consul in 59 BC, had failed in securing the election to the consulship of his ally Lucius Lucceius. Nevertheless, with the combined strength of the triumvirate, Caesar was largely able to circumvent the authority of Bibulus and the optimates.

Bibulus' only major act as consul was to veto Caesar's bill giving land in Campania to Pompey's soldiers, and to then declare that the rest of the days on which the Centuriate Assembly could meet would be religious holidays. Caesar presented his bill at the Assembly anyway, and when Bibulus tried to intervene, the crowd broke his fasces and dumped feces on him. He retired from the Forum, leaving Caesar with complete control over the consulship, although he occasionally issued complaints against Caesar, which led to attacks on his house from Caesar's supporters, the populares. For the rest of the year, the populares joked that the two consuls were really "Julius and Caesar"; the "optimates" returned the joke by referring to the Bibulus' co-consul as the "Queen of Bithynia," an allusion to Caesar's alleged love affair with the king of Bithynia. Bibulus spent the remainder of his term sequestered in his house where he claimed he was watching for omens, an act that purported to technically invalidate all legislation passed that year.

As a senator, in 52 BC, he supported Pompey, who was by then a political enemy of Caesar. Bibulus and Cato Uticencis allowed Pompey to serve as sole consul in 52 BC after the murder of Publius Clodius. In 51 BC he became governor of Syria, but offended the army there by claiming a victory which had been won before he arrived.

In 48 BC he allied with Pompey against Caesar, commanding Pompey's navy in the Adriatic. He captured Caesar's fleet, leaving Caesar stranded in Epirus, although this was a small feat as Caesar went on to defeat Pompey at the Battle of Pharsalus. Bibulus died later in 48 BC.

Bibulus was married twice. From the first marriage he had three sons, including the later statesman Lucius Calpurnius Bibulus. His two eldest sons were killed in Egypt by some of the soldiery which Aulus Gabinius had left there after having restored Ptolemy Auletes to the throne. His second wife was Cato's daughter Porcia.