Gnaeus Papirius Carbo (c. 130s BC – 82 BC) was a three-time consul of ancient Rome.
A member of the Carbones of the plebeian gens Papiria, and nephew of Gaius Papirius Carbo (consul of 120), he was a strong supporter of the Marian party, and took part in the blockade of Rome (87 BC). In 85 BC he was chosen by Lucius Cornelius Cinna as his colleague in the consulship, and extensive preparations were made for carrying out war in Greece against Lucius Cornelius Sulla, who had announced his intention of returning to Italy. Cinna and Carbo declared themselves consuls for the following year, and large bodies of troops were transported across the Adriatic Sea; but when Cinna was murdered by his own soldiers, who refused to engage in civil war, Carbo was obliged to bring them back.
In 82 BC Carbo, then consul for the third time with Gaius Marius the Younger, fought an indecisive engagement with Sulla near Clusium, but was defeated with great loss in an attack on the camp of Sulla's general, Quintus Caecilius Metellus Pius near Faventia. Although he still had a large army and the Samnites remained faithful to him, Carbo was so disheartened by his failure to relieve Praeneste, where Marius the Younger had taken refuge, that he decided to leave Italy. He first fled to Africa, thence to the island of Cossyra (Pantelleria), where he was arrested, taken in chains before Gnaeus Pompey Magnus at Lilybaeum and put to death.