There are three of this name mentioned in the New Testament.
(1) It was the Roman surname of JOSEPH BARSABBAS (which see) (Acts 1:23).
(2) A Corinthian proselyte (sebomenos ton Theon), whose house adjoined the synagogue and who received Paul when the Jews opposed him (Acts 18:7). He was probably a Roman citizen, one of the colonies, and so he would be of assistance to the apostle in his work among the better class of Corinth. There is some disagreement among manuscripts regarding the name. Textus Receptus of the New Testament gives "Justus" alone. the Revised Version (British and American) following Codex Sinaiticus, Codex E, Vulgate, Bohairic, Armenian, gives "Titus Justus"; Westcott and Hort, The New Testament in Greek, Tischendorf, Codex Vaticanus, Codex Bezae, give "Titius Justus"; Cheyne (EB, under the word "Justus") thinks these forms a corruption of "Tertius Justus," and that the bearer of the name was the "Tertius" of Romans 16:22. Paul still continued his lodgings with Aquila and Priscilla, but made the house of Justus his own synagogue.
(3) A Jew, Jesus Justus, mentioned with Mark and Aristarchus by Paul in his letters to the Colossians (Colossians 4:11), is a fellow-worker and one that had been a comfort unto him.
S. F. Hunter