The plebs was the general body of free land-owning Roman citizens (as distinguished from slaves and the capite censi) in Ancient Rome. Members of the plebs were also distinct from the higher order of the patricians. A member of the plebs was known as a plebeian ( /plɨˈbiːən/; Latin: plebeius). This term is used today to refer to one who is or appears to be of the middle or lower order; however, in Rome plebeians could become quite wealthy and influential. In fact, Nero, a Roman emperor, was born a "pleb". His success was not uncommon and approximately 30% of Roman emperors were "plebs".^{[citation needed]}

In Latin the word plebs is a singular collective noun, and its genitive is plebis. Multiple "plebs" are "plebes".

The origin of the separation into orders is unclear, and it is disputed whether the Romans were divided under the early kings into patricians and plebeians, or whether the clientes (or dependents) of the patricians formed a third group. The nineteenth century historian Barthold Georg Niebuhr held that plebeians began to appear at Rome during the reign of Ancus Marcius, possibly foreigners settling in Rome as naturalized citizens. In any case, at the outset of the Roman Republic, plebeians were excluded from magistracies and religious colleges. Later on, after a general strike by the plebeians^{[citation needed]}, the Law of the Twelve Tables was promulgated, and explicitly forbade intermarriage in Tabula XI (a prohibition which was eventually reversed by the Lex Canuleia). However, before the Twelve Tables plebeians were forbidden to know any laws, but were still punished for breaking them. Despite these inequalities, plebeians still belonged to gentes, served in the army, but very rarely became military leaders.