Publius Falcidius was an Ancient Roman Tribune of the Plebs in 40 BCE, of the gens Falcidia.
He was the author of the Lex Falcidia de Legatis, a law on inheritance which remained in force in the sixth century CE, since it was incorporated by Justinian in the Institutes. It is remarkable that Cassius Dio mistakes its import. He says that the heir, if unwilling to take the inheritance, was allowed by the Falcidian law to refuse it on taking a fourth part only. But the Lex Falcidia enacted that at least a fourth of the estate or property of the testator should be secured to the heir named in the testament.
The Falcidius mentioned by Cicero in his speech for the Lex Manilia had the praenomen Caius. He had been Tribune of the Plebs and legatus, but in what year is unknown.