Hippocrates was also the name of a tyrant
He attained the throne in 498B.C. following the assassination of his brother Cleander. He formed a large army of mercenaries and set about subduing his Greek and Sicel neighbours. His empire stretched in a band from the south to the east coast of Sicily. He was allied with the city of Zancle however in 493B.C. he assisted refugees from Samos in capturing the city. In 492 he defeated the Syracusans in battle at the Helorus River. However he was unable to capture Syracuse itself and he decided to allow Corinth and Corcyra to mediate a peace between them. Hippocrates was killed by Sicels in 491B.C. close to Hybla.
There was also a mathmatician and astronomer named Hippocrates towards the end of the fifth century B.C..
Hippocrates made several advances in the field of geometry and he compiled the first "Elements" of Geometry, which contained several ideas echoed in Euclid's work. Aristotle tells us that he developed a theory of comets.