Tacitus on Nero and the Christians.

The Neronian persecution of the sect whose founder was Christ.

One of the ancient pagan testimonia.

Also of interest, the Testimonium of Josephus and its connections with other ancient texts. Refer also to The Chrestianos Issue in Tacitus Reinvestigated, an article by Erik Zara concerning the original reading of the the second Medicean manuscript of the Annals.

Tacitus, Annals 15.44 (translation modified slightly from Church and Brodribb):

Et haec quidem humanis consiliis providebantur. mox petita {a} dis piacula aditique Sibyllae libri, ex quibus supplicatum Volcano et Cereri Proserpinaeque, ac propitiata Iuno per matronas, primum in Capitolio, deinde apud proximum mare, unde hausta aqua templum et simulacrum deae perspersum est; et sellisternia ac pervigilia celebravere feminae, quibus mariti erant.

Such indeed were the precautions of human wisdom. The next thing was to seek means of propitiating the gods, and recourse was had to the Sibylline books, by the direction of which prayers were offered to Vulcanus, Ceres, and Proserpina. Juno, too, was entreated by the matrons, first in the capitol, then on the nearest part of the coast, whence water was procured to sprinkle the fane and image of the goddess. And there were sacred banquets and nightly vigils celebrated by married women.

Sed non ope humana, non largitionibus principis aut deum placamentis decedebat infamia, quin iussum incendium crederetur. ergo abolendo rumori Nero subdidit reos et quaesitissimis poenis adfecit quos per flagitia invisos vulgus Christianos* appellabat. auctor nominis eius Christus Tiberio imperitante per procuratorem Pontium Pilatum supplicio adfectus erat; repressaque in praesens exitiabilis superstitio rursum erumpebat, non modo per Iudaeam, originem eius mali, sed per urbem etiam, quo cuncta undique atrocia aut pudenda confluunt celebranturque. igitur primum correpti qui fatebantur, deinde indicio eorum multitudo ingens haud proinde in crimine incendii quam odio humani generis convicti sunt. et pereuntibus addita ludibria, ut ferarum tergis contecti laniatu canum interirent aut crucibus adfixi aut flammandi atque, ubi defecisset dies, in usu{m} nocturni luminis urerentur. hortos suos ei spectaculo Nero obtulerat, et circense ludicrum edebat, habitu aurigae permixtus plebi vel curriculo insistens. unde quamquam adversus sontes et novissima exempla meritos miseratio oriebatur, tamquam non utilitate publica, sed in saevitiam unius absumerentur.

* This may originally have been Chrestianos, with an e instead of an i. Refer to the IIDB discussion of the so-called second Medicean 2 manuscript of the Annals, and especially to The Chrestianos Issue in Tacitus Reinvestigated, by Erik Zara; I have also uploaded a photo of the page of this manuscript which contains this portion of the text.

But all human efforts, all the lavish gifts of the emperor, and the propitiations of the gods, did not banish the sinister belief that the conflagration was the result of an order. Consequently, to get rid of the report, Nero fastened the guilt and inflicted the most exquisite tortures on a class hated for their abominations, called Christians by the populace. Christus, from whom the name had its origin, suffered the extreme penalty during the reign of Tiberius at the hands of one of our procurators, Pontius Pilatus, and a most mischievous superstition, thus checked for the moment, again broke out not only in Judea, the first source of the evil, but even in Rome, where all things hideous and shameful from every part of the world find their centre and become popular. Accordingly, an arrest was first made of all who pleaded guilty; then, upon their information, an immense multitude was convicted, not so much of the crime of firing the city as of hatred against mankind. Mockery of every sort was added to their deaths. Covered with the skins of beasts, they were torn by dogs and perished, or were nailed to crosses, or were doomed to the flames and burnt, to serve as a nightly illumination when daylight had expired. Nero offered his gardens for the spectacle, and was exhibiting a show in the circus while he mingled with the people in the dress of a charioteer or stood aloft on a car. Hence, even for criminals who deserved extreme and exemplary punishment, there arose a feeling of compassion; for it was not, as it seemed, for the public good but rather to glut the cruelty of one man that they were being destroyed.

Sulpicius Severus, early in century V, uses this Tacitean text in Chronicle 2.29.1-4a:

Interea abundante iam Christianorum multitudine accidit ut Roma incendio conflagraret Nerone apud Antium constituto. sed opinio omnium invidiam incendii in principem retorquebat, credebaturque imperator gloriam innovandae urbis quaesisse. neque ulla re Nero efficiebat, quin ab eo iussum incendium putaretur. igitur vertit invidiam in Christianos, actaeque in innoxios crudelissimae quaestiones; quin et novae mortes excogitatae, ut ferarum tergis contecti laniatu canum interirent, multi crucibus affixi aut flamma usti, plerique in id reservati, ut cum defecisset dies, in usum nocturni luminis urerentur. hoc initio in Christianos saeviri coeptum. post etiam datis legibus religio vetabatur, palamque edictis propositis Christianum esse non licebat. tum Paulus ac Petrus capitis damnati; quorum uni cervix gladio desecta, Petrus in crucem sublatus est.

In the meantime, the number of the Christians being now very large, it happened that Rome was destroyed by fire while Nero was stationed at Antium. But the opinion of all cast the odium of causing the fire upon the emperor, and the emperor was believed in this way to have sought for the glory of building a new city. And in fact, Nero could not by any means that he tried escape from the charge that the fire had been caused by his orders. He therefore turned the accusation against the Christians, and the most cruel tortures were accordingly inflicted upon the innocent. Nay, even new kinds of death were invented, so that, being covered in the skins of wild beasts, they perished by being devoured by dogs, while many were crucified or slain by fire, and not a few were set apart for this purpose, that, when the day came to a close, they should be consumed to serve for light during the night. It was in this way that cruelty first began to be manifested against the Christians. Afterward, too, their religion was prohibited by laws which were given, and by edicts openly set forth it was proclaimed unlawful to be a Christian. At that time Paul and Peter were condemned to capital punishment, of whom the one was beheaded with a sword, while Peter suffered crucifixion.

The following text from Sulpicius Severus is sometimes thought to derive from one of the lost books of Tacitus. Chronicle 2.30.6-7:

Fertur Titus adhibito consilio prius deliberasse an templum tanti operis everteret. etenim nonnullis videbatur aedem sacratam ultra omnia mortalia illustrem non oportere deleri, quae servata modestiae Romanae testimonium, diruta perennem crudelitatis notam praeberet. at contra alii et Titus ipse evertendum templum in primis censebant quo plenius Iudaeorum et Christianorum religio tolleretur, quippe has religiones, licet contrarias sibi, iisdem auctoribus profectas. Christianos ex Iudaeis extitisse; radice sublata, stirpem facile perituram.

Titus is reported, after a council was summoned, to have deliberated beforehand whether he should destroy the temple, it being of such workmanship. For it seemed to some that a sacred edifice, illustrious beyond all mortal things, ought not to be brought down, because, if preserved, it would be a testimony to Roman moderation, but, if destroyed, would offer a perennial notice of [Roman] cruelty. But, on the other hand, Titus himself, along with others, decided that first of all the temple should be destroyed so that the religion of the Jews and of the Christians might be removed all the more, since these religions, although contrary to one another, came forth from the same authors. The Christians rose up from the Jews; if the root were taken away, the stem would easily perish.

The Latin Library has this text by Sulpicius Severus available online in Latin.

Richard Carrier in an online article and Eric Laupot in the article to which Carrier is responding point out that Paulus Orosius, a contemporary of Severus, has a very similar passage in his History Against the Pagans 7.9.4-6 (Carrier provides the Latin and a translation, which I have slightly modified):

Quod tamen postquam in potestatem redactum opere atque antiquitate suspexit, diu deliberavit utrum tamquam incitamentum hostium incenderet, an in testimonium victoriae reservaret. sed ecclesia dei iam per totum orbem uberrime germinante, hoc tamquam effetum ac vacuum, nullique usui bono commodum, arbitrio dei auferendum fuit. itaque Titus imperator ab exercitu pronuntiatus, templum in Hierosolymis incendit.

After seizing [the temple], which he nevertheless admired because of its workmanship and antiquity, Titus deliberated for a long time whether to set on fire this inspiration of the enemy, or spare it as a testimony to his victory. But, since the church of God had already grown very fruitfully throughout the whole world, this [temple] was essentially vain and pointless, and suitable for no good use to anyone, so by the decision of God it had to be destroyed. And so, once Titus was pronounced emperor by the army, he burned the temple in Jerusalem.

The heart of the mention of Christ and Christianity in Tacitus, Annals 15.44, reads as follows:

Ergo abolendo rumori Nero subdidit reos et quaesitissimis poenis adfecit quos per flagitia invisos vulgus Christianos appellabat. auctor nominis eius Christus Tiberio imperitante per procuratorem Pontium Pilatum supplicio adfectus erat; repressaque in praesens exitiabilis superstitio rursum erumpebat, non modo per Iudaeam, originem eius mali, sed per urbem etiam, quo cuncta undique atrocia aut pudenda confluunt celebranturque.

Therefore, in order to get rid of the rumor, Nero laid the matter upon those whom the crowd called Chrestians for their secret abominations and inflicted the most exquisite pentalties on them. Christ, the author of the name, had been afflicted with capital punishment through the procurator Pontius Pilate while Tiberius was emperor, and the mischievous superstition, repressed for the moment, again erupted, not only in Judea, the origin of this evil, but also throughout Rome, where all atrocities and shameful things from everywhere converge and are celebrated.

Tertullian, Apologeticum 3.5-6:

Christianus vero, quantum interpretatio est, de unctione deducitur. sed et cum perperam Chrestianus pronuntiatur a vobis, nam nec nominis certa est notitia penes vos, de suavitate vel benignitate compositum est. oditur itaque in hominibus innocuis etiam nomen innocuum. at enim secta oditur in nomine utique sui auctoris.

Christian [as a word] indeed, as much as it is to be interpreted, is derived from [the word] anointing. And even when it is falsely pronounced Chrestian by you, for neither is there any certain notice taken of the name among you, it is made up of sweetness or benignity. Thus even an innocent name is hated among innocent men. But indeed the sect is hated in the name of its author.

Tacitus writes in Annals 4.73:

Ac simul utrumque exercitum Rheno devectum Frisiis intulit, soluto iam castelli obsidio et ad sua tutanda degressis rebellibus.

And, simultaneously conveying each army down the Rhine, he cast them at the Frisii, the siege of the castle being immediately dissolved and the rebels dispersed to guard their own.

J. L. Berggren, Ptolemy's Geography, page 28, note 34:

"Siatoutanda" (Geography 2.11), perhaps from the phrase, "The rebels having departed to ensure their safety (ad sua tutanda)" (Tacitus, Ann{als} 4.73, Loeb 4.129). The resemblance (which was first noticed by H. Müller in 1837) may, however, be accidental....

If Müller is correct, and the resemblance is not accidental, then Ptolemy mistakenly took the phrase ad sua tutenda (to guard their own possessions) as ad Suatutenda or ad Siatutenda (to Siatutenda), thus demonstrating that Ptolemy (early century II) knew the Annals. Ptolemy writes at 2.11 (text simplified from that available at LacusCurtius; latitude and longitude omitted):

Πολεις δε τιθενται κατα την Γερμανιαν εν μεν τω αρκτικω κλιματι αιδε· Φληουμ, Σιατουτανδα, Τεκελια, Φαβιρανον, Τρηουα, Λευφανα, Λιριμιρις, Μαριωνις, Μαριωνις ετερα, Κοινοηνον, ΚιστουΙα, Αλειος, Λακιβρουργιον, Βουνιτιον, Ουιρουνον, Ουριτιον, Ρουγιον, Σκουργον, Ασκαυκαλις.

Oppida vero per Germaniam ponuntur in climate septentrionali haec: Phleum, Siatutanda, Tecelia, Fabiranum, Treva, Leufana, Lirimiris, Marionis, another Marionis, Coenoënum, Cistuia, Alisus, Laciburgium, Bunitium, Virunum, Viritium, Rugium, Scurgum, Ascaucalis.

And these cities are placed throughout Germany in the northern climate: Phleum, Siatutanda, Tecelia, Fabiranum, Treva, Leufana, Lirimiris, Marionis, another Marionis, Coenoënum, Cistuia, Alisus, Laciburgium, Bunitium, Virunum, Viritium, Rugium, Scurgum, Ascaucalis.