Ochlocracy (Greek: ὀχλοκρατία, okhlokratía; Latin: ochlocratia) or mob rule is government by mob or a mass of people, or the intimidation of legitimate authorities. As a pejorative for majoritarianism, it is akin to the Latin phrase mobile vulgus meaning "the fickle crowd", from which the English term "mob" was originally derived in the 1680s.

Ochlocracy ("rule of the general populace") is democracy ("rule of the people") spoiled by demagoguery, "tyranny of the majority" and the rule of passion over reason, just like oligocracy ("rule of a few") is aristocracy ("rule of the best") spoiled by corruption. Ochlocracy is synonymous in meaning and usage to the modern, informal term "Mobocracy," which emerged from a much more recent colloquial etymology.

The term appears to have been coined by Polybius in his Histories (6.4.6). He uses it to name the 'pathological' version of popular rule in opposition to the good version, which he refers to as democracy. There are numerous mentions of the word "ochlos" in the Talmud (where "ochlos" refers to anything from "mob," "populace" to "armed guard"), as well as in Rashi, a Jewish commentary on the Bible. The word is recorded in English since 1584, derived from the French ochlocratie (1568), which stems from the original Greek okhlokratia, from okhlos "mob" and kratos "rule, power, strength"