Consul (abbrev. cos.; Latin plural consules) was the highest elected office of the Roman Republic and an appointive office under the Empire. The title was also used in other city states and also revived in modern states, notably in the First French Republic. The relating adjective is consular, from the Latin consularis (which has been used, substantiated, as a title in its own right).

While many cities (as in Gaul) had a double-headed chief magistracy, often another title was used, such as Duumvir or native styles such as Meddix, but Consul was used in some.

It was not uncommon for an organisation under Roman private law to copy the terminology of state and city institutions for its own statutory agents. The founding statute, or contract, of such an organisation was called lex, 'law'. The people elected each year were patricians, members of the upper class.

The city-state of Genoa, unlike ancient Rome, bestowed the title of Consul on various state officials, not necessarily restricted to the highest. Among these were Genoese officials stationed in various Mediterranean ports, whose role included helping Genoese merchants and sailors in difficulties with the local authorities. This institution, with its name, was later emulated by other powers and is reflected in the modern usage of the word (see Consul (representative)).