Cleomenes III is the King of Sparta from 235-222 BCE.

He succeeds to the Agiad throne of Sparta after his father, Leonidas II in 235 BCE.

From 229 BCE to 222 BCE, Cleomenes wages war against the Achaean League under Aratus of Sicyon.

Domestically, he is known for his attempt to reform the Spartan state.

After being defeated by the Acheans in the Battle of Sellasia in 222 BCE, he flees to Ptolemaic Egypt.

After a failed revolt in 219 BCE, he commits suicide.