Members of this gens appear during the earliest period of the Republic, but the family only attained prominence from the time of the Second Punic War.
According to legend, he volunteered to infiltrate the camp of Lars Porsena, the king of Clusium, who besieged Rome c. 508 BC, and who may in fact have captured and held the city for some time.
Brought before the king, Mucius declared that he was but one of three hundred Roman men who had sworn to carry out this mission, or die in the attempt.
[1] But assuming that the would-be assassin was a real person, all of the other Mucii known to history seem to have been plebeians, suggesting that there may never have been a patrician family of this name.
The only praenomina used by the Mucii mentioned during the Republic were Publius, Quintus, and Gaius, each of which were among the most common names at all periods of Roman history.