Agis I

Agis I (fl. c. 930–900 BCE) was an early, and possibly the first historical, king of the ancient Greek city-state of Sparta. He is the eponymous founder of the Agiad dynasty, one of Sparta's two joint royal families (the other being the Eurypontids), both of which claimed descent from the mythical hero Heracles. Agis I succeeded his father, Eurysthenes, who is often considered a purely legendary figure.

Reigning during the Greek Dark Ages, Agis is traditionally credited with consolidating Dorian power in Laconia. Ancient sources, notably the historian Ephorus, attribute to him the key military campaign that captured the coastal Achaean town of Helos. The inhabitants of Helos were subdued and enslaved, reportedly giving rise to the Spartan class of state-owned serfs known as helots, whose forced labor underpinned the entire Spartan military society.

Agis's reign is seen as a pivotal time in the formation of the Spartan state, as he unified several dispersed Laconian villages into the nascent Spartan polity. While some ancient chroniclers suggest he had a long reign of over 30 years, another source indicates only one year; modern historians typically place his activity around the end of the 10th century BCE. He was succeeded by his son, Echestratus.