Arruns Tarquinius was the brother of Lucius Tarquinius Superbus, the seventh and last King of Rome. According to most ancient authors, Arruns and his brother were the sons of Lucius Tarquinius Priscus, the fifth Roman king, and Tanaquil. However, in some sources they described as grandsons; their father may have been a certain Gnaeus Tarquinius, who according to an Etruscan tradition was defeated and killed by the heroes Aulus and Caelius Vibenna, together with a certain Macstarna. Apparently the Etruscan equivalent of the Latin word magister, Macstarna has been identified with Servius Tullius, the sixth King of Rome.