Ninus (Greek: Νίνος), according to Greek historians writing in the Hellenistic period and later, was accepted as the eponymous founder of Nineveh (also called Νίνου πόλις "city of Ninus" in Greek), ancient capital of Assyria. His name is not attested on the Assyrian King List or in any cuneiform literature; he does not seem to represent any one personage known to modern history, and is more likely a conflation of several real and/or fictional figures of antiquity, as seen to the Greeks through the mists of time.
Many early accomplishments are attributed to him, such as training the first hunting dogs, and taming horses for riding. For this accomplishment, he is sometimes represented in Greek mythology as a centaur.
The figures of King Ninus and Queen Semiramis first appear in the history of Persia written by Ctesias of Cnidus (c. 400 BC), who claimed, as court physician to Artaxerxes II, to have access to the royal historical records. Ctesias' account was later expanded on by Diodorus Siculus. Ninus continued to be mentioned by European historians (e.g. Alfred the Great), even up until knowledge of cuneiform enabled a more precise reconstruction of Assyrian and Babylonian history from the mid 19th century onwards.
He was said to have been the son of Belus or Bel, a name that may represent a Semitic title such as Ba'al, "lord". According to Castor of Rhodes (apud Syncellus p. 167), his reign lasted 52 years, its commencement falling in 2189 BC according to Ctesias. He was reputed to have conquered the whole of western Asia in 17 years with the help of Ariaeus, king of Arabia, and to have founded the first empire, defeating the legendary kings Barzanes of Armenia (whom he spared) and Pharnus of Media (whom he had crucified).