A polemarch (//, from Ancient Greek: πολέμαρχος, polemarchos) was a senior military title in various ancient Greek city states (poleis). The title is composed out of the polemos (war) and archon (ruler/leader) and translates as "warleader" or "warlord", one of the nine archontes (ἄρχοντες) appointed annually in Athens. The name indicates that the polemarchos' original function was to command the army; presumably the office was created to take over this function from the king. Eventually military command was transferred to the strategoi (στρατηγοί), but the date and stages of the transfer are not clear. At Marathon in 490 BC the strategoi debated and voted on strategy, but Callimachus the polemarch had a casting vote, and he was the leader; it is disputed whether that means he was the real, or merely the titular commander-in-chief. Certainly the polemarchos no longer had military authority after 487/486 BC, when archontes were appointed by lot and it could not be expected that every polemarch would make a competent commander.
Thereafter the polemarch's main functions were legal. In the 4th Century BC, he had charge of trials of metics' family, inheritance, and status cases, and of the allocation to tribe-judges (members of the Forty) of other private actions involving metics; and it is likely that at an earlier period, his responsibilities for cases involving aliens were more extensive. He also conducted certain sacrifices and arranged the funeral ceremony for men killed in war.
The most famous polemarchos is probably the Athenian archōn polemarchos. He was of the magistrates called archons. Originally, the polemarch was a commander of the army, but after 487/486 BC, when the Athenian magistrates were appointed by lot, the military duties were handled by the strategoi. This office also had religious and legal functions.
In the new structure of the Spartan Army introduced sometime in the Peloponnesian War, a polemarchos was the commander of a mora of 576 men, one of six in the Spartan army on campaign.(Xenophon, Rep. Lac. XI 4.) On occasion however they were appointed to head armies. The six Spartan polemarchoi seem to have been on equal power to kings at expeditions outside Laconia and were usually descendants of the royal houses (Herodotus, VII 173.) They were part of the royal army council and the royal escort (δαμοσία) (Xenophon, Hell. VI 4 § 14.) They were supported or represented by officers (συμφορεῖς). The polemarchoi were also responsible for public meals, since, by the laws of Lycurgus, the Lacedaemonians would eat and fight in the same group. Next to their military and connected responsibilities, the polemarchoi were responsible for some civil and juridical tasks (not unlike the archōn polemarchos in Athens).
In modern use, some fraternities, notably Kappa Alpha Psi, label their chapters' leaders as Polemarchs.
This position was featured in Orson Scott Card's novel Ender's Game. In the novel, the position of polemarch was charged with the supreme command of humanity's space fleets, the International Fleet. The Polemarch, along with the positions of Strategos and Hegemon, was one of the three most powerful people alive.
This title was also given to the DC Comics character Artemis of Bana-Mighdall, an Amazon in the Wonder Woman comic books. For a period Artemis served as Paradise Island's co-ruler alongside fellow Amazon Philippus. Whereas Philippus oversaw the day-to-day rule of the island, Artemis oversaw its military aspects.