The name Justus is a boy's name of German, Latin, Dutch origin meaning "just". Justus and is often added to lists like Cool Boy Names From Ancient Cultures and discussed in our forums with posts like "Drop your least favorite (boys)".
From the experts:
More unusual than Justin, less word-like than Justice, this New Testament name could make an intriguing choice. After being off the popularity lists from 1904 to 1993, it is now being used in steady numbers.
There have been three notable saints named Justus: St. Justus of Canterbury, who was instrumental in the conversion of Anglo-Saxons to Roman Christians and became the fourth Bishop of Canterbury, and the martyred St. Justus of Beauvais and St. Justus of Lyons.