Tullus Hostilius was the legendary third king of Rome. He succeeded Numa Pompilius and was succeeded by Ancus Marcius. Unlike his predecessor, Tullus was known as a warlike king who according to the Roman Historian Livy, believed the more peaceful nature of his predecessor had weakened Rome. It has been attested that he sought out war and was even more warlike than the first king of Rome, Romulus. Accounts of the death of Tullus Hostillus vary. In the mythological version of events Livy describes, he had angered Jupiter who then killed him with a bolt of lightning. Non mythological sources on the other hand describe that he died of plague.
Tullus Hostilius was the grandson of Hostus Hostilius, who had fought with Romulus and died during the Sabine invasion of Rome.
The principal feature of Tullus' reign was the defeat of Alba Longa. After Alba Longa was beaten, Alba Longa became Rome's vassal state.
Hostilius during his reign created the college of the Fetiales that concluded all treaties in the name of Rome.