Quadratus of Athens.

One of the Christian apologists.

Attributed text(s).
Apology.

Text(s) available.
On site: Fragment (present page).
Early Christian Writings: Fragment (English only).

Related text(s).
Apology of Aristides.

Useful links.
Quadratus at Early Christian Writings.
Quadratus in the Catholic Encyclopedia.

Quadratus was a Christian apologist who wrote an apology to Hadrian (emperor 117-138). Of this apology only a single Eusebian quotation survives. Quadratus is sometimes reckoned among the apostolic fathers, but I would prefer to group him with the Christian apologists.

Eusebius, History of the Church 4.3.1-3:

Τραιανου δε εφ ολοις ετεσιν εικοσι την αρχην μησιν εξ δεουσι κρατησαντος, Αιλιος Αδριανος διαδεχεται την ηγεμονιαν. τουτω Κοδρατος λογον προσφωνησας αναδιδωσιν, απολογιαν συνταξας υπερ της καθ ημας θεοσεβειας, οτι δη τινες πονηροι ανδρες τους ημετερους ενοχλειν επειρωντο. εισετι δε φερεται παρα πλειστοις των αδελφων, αταρ και παρ ημιν το συγγραμμα, εξ ου κατιδειν εστιν λαμπρα τεκμηρια της τε του ανδρος διανοιας, και της αποστολικης ορθοτομιας.

And, when Trajan had ruled for twenty whole years minus six months, Aelius Hadrian succeeded to leadership. To him Quadratus addressed and gave a treatise, having composed an apology on behalf of our religion, since indeed some evil men were trying to trouble our own. And it is still extant among many of the brethren, and the writing is also with us, from which can be seen shining proof both of the understanding of the man and of his apostolic orthodoxy.

Ο δ αυτος την καθ εαυτον αρχαιοτητα παραφαινει δι ων ιστορει ταυτα ιδιαις φωναις· Του δε σωτηρος ημων τα εργα αει παρην, αληθη γαρ ην· οι θεραπευθεντες, οι ανασταντες εκ νεκρων, οι ουκ ωφθησαν μονον θεραπευομενοι και ανισταμενοι, αλλα και αει παροντες, ουδε επιδημουντος μονον του σωτηρος αλλα και απαλλαγεντος, ησαν επι χρονον ικανον ωστε και εις τους ημετερους χρονους τινες αυτων αφικοντο.

And he himself makes apparent his own antiquity through these things that he records in his own words: But the works of our savior were always present, for they were true. Those who were healed, those who rose from the dead, who not only looked as though healed and risen, but also were always present, not only while the savior was sojourning but even after he left, were around for enough time so as that some of them stayed even unto our own times.

Τοιουτος μεν ουν ουτος. και Αριστειδης δε πιστος ανηρ της καθ ημας ορμωμενος ευσεβειας, τω Κοδρατω παραπλησιως υπερ της πιστεως απολογιαν επιφωνησας Αδριανω καταλελοιπε. σωζεται δε γε εις δευρο παρα πλειστοις και η τουτου γραφη.

Such was this man. And Aristides also, a faithful man and devoted to our religion, has left behind just as Quadratus an apology on behalf of the faith addressed to Hadrian. The writing of this man too is preserved hither by very many.

Jerome also mentions Quadratus. Chapter 19 of On Famous Men he dedicates to the apologist (English translation slightly modified from the Quadratus page on Early Christian Writings, which in turn comes from the Christian Classics Ethereal Library):

Quadratus, apostolorum discipulus, Publio, Athenarum episcopo, ob Christi fidem martyrio coronato in locum eius substituitur et ecclesiam grandi terrore dispersam fide et industria sua congregat. cumque Hadrianus Athenis exegisset hiemem invisens Eleusinam et omnibus paene Graeciae sacris initiatus que praecepto imperatoris vexare credentes, porrexit ei librum pro nostra religione compositum valde necessarium plenumque rationis et fidei et apostolica doctrina dignum. in quo et antiquitatem suae aetatis ostendens ait plurimos a se visos, qui sub domino variis in Iudaea oppressi calamitatibus sanati fuerant, et qui a mortuis resurrexerant.

Quadratus, disciple of the apostles, after Publius bishop of Athens had been crowned with martyrdom on account of his faith in Christ, was substituted in his place, and by his faith and industry gathered the church scattered by reason of its great fear. And, when Hadrian passed the winter at Athens to witness the Eleusinian mysteries and was initiated into almost all the sacred mysteries of Greece, those who hated the Christians took opportunity without instructions from the emperor to harass the believers. At this time he presented to Hadrian a work composed in behalf of our religion, indispensable, full of sound argument and faith and worthy of the apostolic teaching. In which, illustrating the antiquity of his period, he says that he has seen many who, oppressed by various ills, were healed by the Lord in Judea as well as some who had been raised from the dead.

What follows is chapter 20, ibidem, on Aristides (English translation slightly modified from that at the Christian Classics Ethereal Library):

Aristides Atheniensis, philosophus eloquentissimus et sub pristino habitu discipulus Christi, volumen nostri dogmatis continens rationem eodem tempore quo et Quadratus, Hadriano principi, dedit, id est, apologeticum pro Christianis, quod usque hodie perseverans apud philologos ingenii eius indicium est.

Aristides, a most eloquent Athenian philosopher, and a disciple of Christ while yet retaining his original garb [as a philosopher], presented a work to Hadrian at the same time that Quadratus presented his. The work contained a systematic statement of our doctrine, that is, an apology for the Christians, which is still extant and is regarded by philologians as an index of his genius.