The name Helvidius does not occur in Roman history until the latter half of the first century B. C. (Cic. Clu. 70.) Under Nero and the Flavian Caesars it was renowned for earnest, but fruitless, patriotism. The connection of P. Helvidius Rufus with Larinum (Cic. l.c.), a Frentanian municipium (Plin. Nat. 3.12), makes it probable that the family was originally Sabellian. The Helvidii had the surnames Priscus and Rufus. The only Helvidius who had no cognomen, or whose cognomen has, perhaps, dropped out of the MSS., is the following:--
A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890