Thallus (historian) in Wikipedia
Thallus (Greek: Θαλλός) sometimes spelled Thallos, was a early Samaritan historian who wrote in Koine Greek. Scholars believe that his is the earliest reference to the historical Jesus, written about 20 years after the Crucifixion. Around 55 AD, he wrote a three-volume history of the Mediterranean world from before the Trojan War to about 50 AD. Most of his work, like the vast majority of ancient literature, perished, but not before it was preserved by Sextus Julius Africanus in his History of the World.   
The works are are important because they confirm the historicity of Jesus. Thallos details the Crucifixion of Jesus but explains that the darkness that fell over the land at the time of Jesus' death was not a supernatural miracle, but an merely an eclipse. This would establish a pre-Markan origin for the story spoken of in the Gospel of Mark.  
The fragments of Thallus
1. From the 3 books of Thallus, in which he made a summary in abbreviated fashion from the sack of Troy to the 167th Olympiad [i.e. 109 BC] (Eusebius, Chronicle, I. K125.2)
2. Castor and Thallus [recorded] Syrian events. (Africanus, in Eusebius, PE X.10)
3. The archives of the most ancient races--the Egyptians, Chaldaeans, and Phoenicians--need to be opened, and their citizens must be called upon, through whom knowledge must be provided--a certain Manetho the Egyptian and Berosus the Chaldaean, but also Jerome the Phoenician king of Tyre; and their followers, too: Ptolemy the Mendesian and Menander the Ephesian and Demetrius the Phalerean and king Juba and Apion and Thallus and the one who either proves or refutes these men, Josephus the Jew. (Tertullian, Apologeticum 19)
4. on the whole world there pressed a fearful darkness, and the rocks were rent by an earthquake, and many places in Judea and other districts were thrown down. Thallus calls this darkness an eclipse of the sun in the third book of his Histories, without reason it seems to me. (Africanus, in Syncellus)
5. For Thallus also remembers Belus the ruler of Assyria and Cronos the Titan, asserting that Belus waged war along with the Titans against Zeus and the select gods who were with him, stating at this point: 'and defeated, Ogygus fled to Tartessus. While at that time that region was famous as Akte, now it is called Attica, which Ogygus then took over.' (Theophilus, Ad Autolycum 3.29)
6. For according to the history of Thallus, we find that Belus was born 322 years prior to the Trojan War. (Lactantius, Divine Institutions I.23)
7. And so ... neither Diodorus the Greek nor Thallus, neither Cassius Severus nor Cornelius Nepos, nor any commentator on such ancient matters, prints that Saturn was anything but a man. (Tertullian, Apologeticum 10).
8. Therefore not only all poets, but even all historians and all writers on ancient matters, who have published for posterity his deeds done in Italy, agree he was a man: in Greek, Diodorus and Thallus, and in Latin, Nepos and Cassius and Varro. (Lactantius Div. Int. I.13).
9. All writers of Greek and Roman antiquities tell us that Saturn, the first of his kind, was a man: Nepos knows this, and Cassius in his history, as well as Thallus and Diodorus, say this. (Minucius Felix 21)
10. Regarding the events before the Olympiads, consider how the Attic chronologers reckon: from the time of Ogygus, during whose tenure the first great flood occurred in Attica, while Phoroneus was ruling the Argives, as Acusilaus records, up to the time of the first year of the first Olympiad, the point after which the Greeks consider time to be reckoned more accurately, 1020 years passed, which agrees with those mentioned earlier and with those who were listed in order. For the writers on Athenian history, Hellanicus and Philochorus (who wrote Atthis) and writers on Syrian affairs, Castor and Thallus, and writers on world affairs, Diodorus (who wrote the Library) and Alexander Polyhistor, and some of our contemporaries record these events even more accurately than all the Attic historians. (Africanus, in Eusebius PE X.10)
11. So know this: of all those among us [the Jews] happen to be more ancient than many: [for instance] ... Moses ... as is clear to us in the histories of the Greeks. ... For in the times of Ogygus and Inachus ... they record Moses ... so does Polemon in his first book of his History of the Greeks, and Apion ... and Ptolemaeus the Mendesian, who wrote a history of Egypt, all these men agree. And the writers on Athenian history, Hellanicus and Philochorus (who wrote Atthis), Castor and Thallus and Alexander Polyhistor, and also those most wise of men, Philo and Josephus ... [all these men] mention Moses, as they do the very old and ancient origin of the Jews. (Justin, Cohortatio 9)
12. 41 Assyrian kings ruled the kingdom of the Arabs, who also ruled from the [?] year of the world to the [?] year of the world, enduring all of [?] years from the first of them, Belus, until the 41st king, Macoscolerus, the son of Sardanapallus, as most noted historians agree, including Polybius, Diodorus, Cephalion, Castor, Thallus and others. (Syncellus)
13. After the 70th year of the captivity, Cyrus was king of the Persians in the first year of the 55th Olympiad, as we find in the Library of Diodorus and the Histories of Thallus and Castor, and also in the works of Polybius and Phlegon, but also in those of others who concern themselves with Olympiads: they are all in agreement about the date. (Africanus, in Eusebius PE X.10)
14. Those most wise men, Thallus, Castor [259 F 11], and Polybius [254 F 4]...and among others, Herodotus...and the wise Theophilus, all recorded the chronology of the reign of Croesus. (John Malalas VI).
Thallus is sometimes cited for details on Syrian and Assyrian history. Eusebius of Caesarea in a list of sources mentions his work:
From the three books of Thallus, in which he collects (events) briefly from the fall of Ilion to the 167th Olympiad.
However the text is preserved in an Armenian translation where many of the numerals are corrupt. The fall of Troy is 1184 BC, but the editors, Petermann and Karst, highlight that the end-date of the 167th Olympiad (109 BC) is contradicted by George Syncellus, who quotes Julius Africanus, and suggest that the end-date should read "217th Olympiad", a change of one character in Armenian.
Thallus is first mentioned around AD 180 by Theophilus Bishop of Antioch in his Ad Autolycum ('To Autolycus') 3.29:
Thallus makes mention of Belus, the King of the Assyrians, and Cronus the Titan; and says that Belus, with the Titans, made war against Zeus and his compeers, who are called gods. He says, moreover, that Gygus was smitten, and fled to Tartessus. At that time Gygus ruled over that country, which was then called Acte, but is now named Attica. And whence the other countries and cities derived their names, we think it unnecessary to recount, especially to you who are acquainted with history.
Ho gygos 'that Gygus' is probably an error for Ogygos, referring to the Ogygus associated by chronographers with Attica. See Kings of Athens.
Thallus and Josephus
The name Thallus is too common to make a probable identification with any other known Thallus.
The identication sometimes made with a certain Thallus of Samaria who is mentioned in some editions of Josephus' Antiquities (18.167) fails because that name only appears in those editions because of an idiosyncratic alteration of the text by John Hudson in 1720. Until Hudson's time all texts had ALLOS (meaning "another") not THALLOS. See the external link below to Jacoby and Müller.