Hoi polloi (; from Ancient Greek οἱ πολλοί (hoi polloí) 'the many') is an expression from Greek that means "the many" or, in the strictest sense, "the people". In English, it has been given a negative connotation to signify the masses. Synonyms for hoi polloi include "the plebs" (plebeians), "the rabble", "the masses", "the great unwashed", "riffraff", and "the proles" (proletarians).

The phrase probably became known to English scholars through Pericles' Funeral Oration, as mentioned in Thucydides' History of the Peloponnesian War. Pericles uses it in a positive way when praising the Athenian democracy, contrasting it with hoi oligoi, "the few" (Greek: οἱ ὀλίγοι; see also oligarchy).

Its current English usage originated in the early 19th century, a time when it was generally accepted that one must be familiar with Greek and Latin in order to be considered well educated. The phrase was originally written in Greek letters. Knowledge of these languages served to set apart the speaker from hoi polloi in question, who were not similarly educated.