At least two notable Romans were named Marcus Fulvius Flaccus.

The first, M. Fulvius Q.f. Flaccus, was a consul in 264 BC. He was considered to be the founder of the Flaccus branch of the gens Fulvia. He conquered Velzna, an Etruscan city in central Italy, in 264 BC. it was the last Etruscan city to be taken by the Romans.

The second, M. Fulvius M.f. Flaccus was an ally of the Gracchi. He became an administrator of the agrarian reform in 130 BC, and as a solution to the problem of land division among the allied cities, proposed Roman citizenship for the allies' citizens, thus introducing a question that vexed Roman politics for many years. Elected consul in 125 BC, he was ordered by the Roman Senate to assist Massilia (modern Marseille) against depredations of the Salluvii .

Flaccus conquered much of Gallia Narbonensis, and returned in triumph in 123. In 122 he became tribune along with Gaius Gracchus, and went to found a Roman colony, Colonia Junonia , on the ruins of Carthage. When he and Gracchus failed to win re-election in 121, Flaccus led a mass protest on the Aventine Hill, but the consul Lucius Opimius suppressed it brutally, killing Gracchus and Flaccus among many others.