Galatians 1
19 But other of the apostles saw I none, save James the Lord's brother.
As noted in an earlier post, Eusebius refer to James the Just as being a brother of the Lord. As does Clement.
James is mentioned by Josephus in his massive work Jewish Antiquities. We are told that James was sentenced by the Sanhedrin to be stoned:
"But this younger Ananus, who, as we have told you already, took the high priesthood, was a bold man in his temper, and very insolent; he was also of the sect of the Sadducees, who are very rigid in judging offenders, above all the rest of the Jews, as we have already observed; when, therefore, Ananus was of this disposition, he thought he had now a proper opportunity [to exercise his authority]. Festus was now dead, and Albinus was but upon the road; so he assembled the sanhedrim of judges, and brought before them the brother of Jesus, who was called Christ, whose name was James, and some others, [or, some of his companions]; and when he had formed an accusation against them as breakers of the law, he delivered them to be stoned:" (Jewish Antiquities, 20.9.1)
What else did Eusebius say about James?
He was surnamed “the Just” on account of his virtue
He was the first bishop of Jerusalem
“Then James, whom the ancients surnamed the Just on account of the excellence of his virtue, is recorded to have been the first to be made bishop of the church of Jerusalem. This James was called the brother of the Lord because he was known as a son of Joseph, and Joseph was supposed to be the father of Christ, because the Virgin, being betrothed to him, “was found with child by the Holy Ghost before they came together,” as the account of the holy Gospels shows. But Clement in the sixth book of his Hypotyposes writes thus: “For they say that Peter and James and John after the ascension of our Savior, as if also preferred by our Lord, strove not after honor, but chose James the Just bishop of Jerusalem.” But the same writer, in the seventh book of the same work, relates also the following things concerning him: “The Lord after his resurrection imparted knowledge to James the Just and to John and Peter, and they imparted it to the rest of the apostles, and the rest of the apostles to the seventy, of whom Barnabas was one. But there were two Jameses: one called the Just, who was thrown from the pinnacle of the temple and was beaten to death with a club by a fuller, and another who was beheaded.” Paul also makes mention of the same James the Just, where he writes, “Other of the apostles saw I none, save James the Lord’s brother.” (Eusebius, Book 2, Chapter 1)
“BUT after Paul, in consequence of his appeal to Caesar, had been sent to Rome by Festus, the Jews, being frustrated in their hope of entrapping him by the snares which they had laid for him, turned against James, the brother of the Lord, to whom the episcopal seat at Jerusalem had been entrusted by the apostles. The following daring measures were undertaken by them against him. Leading him into their midst they demanded of him that he should renounce faith in Christ in the presence of all the people.
But, contrary to the opinion of all, with a clear voice, and with greater boldness than they had anticipated, he spoke out before the whole multitude and confessed that our Savior and Lord Jesus is the Son of God. But they were unable to bear longer the testimony of the man who, on account of the excellence of ascetic virtue and of piety which he exhibited in his life, was esteemed by all as the most just of men, and consequently they slew him. Opportunity for this deed of violence was furnished by the prevailing anarchy, which was caused by the fact that Festus had died just at this time in Judea, and that the province was thus without a governor and head.
The manner of James’ death has been already indicated by the above-quoted words of Clement, who records that he was thrown from the pinnacle of the temple, and was beaten to death with a club. But Hegesippus, who lived immediately after the apostles, gives the most accurate account in the fifth book of his Memoirs. He writes as follows: “James, the brother of the Lord, succeeded to the government of the Church in conjunction with the apostles. He has been called the Just by all from the time of our Savior to the present day; for there were many that bore the name of James. He was holy from his mother’s womb; and he drank no wine nor strong drink, nor did he eat flesh. No razor came upon his head; he did not anoint himself with oil, and he did not use the bath. He alone was permitted to enter into the holy place; for he wore not woolen but linen garments. And he was in the habit of entering alone into the temple, and was frequently found upon his knees begging forgiveness for the people, so that his knees became hard like those of a camel, in consequence of his constantly bending them in his worship of God, and asking forgiveness for the people. Because of his exceeding great justice he was called the Just, and Oblias, which signifies in Greek, Bulwark of the people’ and ‘Justice,’ in accordance with what the prophets declare concerning him….
So they went up and threw down the just man, and said to each other, ‘Let us stone James the Just.’ And they began to stone him, for he was not killed by the fall; but he turned and knelt down and said, ‘I entreat thee, Lord God our Father, forgive them, for they know not what they do.’ And while they were thus stoning him one of the priests of the sons of Rechab, the son of the Rechabites, who are mentioned by Jeremiah the prophet, cried out, saying, ‘Cease, what do ye? The just one prayeth for you. And one of them, who was a fuller, took the club with which he beat out clothes and struck the just man on the head. And thus he suffered martyrdom. And they buried him on the spot, by the temple, and his monument still remains by the temple. He became a true witness, both to Jews and Greeks, that Jesus is the Christ. And immediately Vespasian besieged them.”
These things are related at length by Hegesippus, who is in agreement with Clement. James was so admirable a man and so celebrated among all for his justice, that the more sensible even of the Jews were of the opinion that this was the cause of the siege of Jerusalem, which happened to them immediately after his martyrdom for no other reason than their daring act against him”. (Eusebius, Book 2, Chapter 23) Near the bottom of the page.