Dorotheus of Sidon (Greek: Δωρόθεος Σιδώνιος, c. 75 CE - ?? CE) was a 1st-century Greek astrologer and astrological poet,^[1] who, during the Hellenistic Period, wrote a didactic poem on horoscopic astrology in Greek, known as the Pentateuch (Πεντάτευχος; lit. five books; more commonly known in the Western world as Carmen Astrologicum^[2]). The Pentateuch, which was a textbook on Hellenistic astrology, has come down to us mainly from an Arabic translation dating from around 800 AD carried out by Omar Tiberiades (which has been suggested to be a translation of a Middle Persian translation from the original Greek, although this matter is disputed and it is possible that the Arabic translation was indeed done from an original Greek manuscript). The Arabic text, however, does contain interpolations by later Persian hands, but, nevertheless, remains one of our best sources for the practice of astrology during Hellenistic and Roman times , and it was a work of great influence on later Christian, Persian, Arab and medieval astrologers. The late 1st century, a time when Dorotheus is believed to have flourished, was a period of intense astrological development, following two millennia of accumulated tradition.

Very little is known about Dorotheus himself. Dorotheus most likely lived and worked in Alexandria, in Egypt, which, in addition to being the most important scholastic center in the Hellenistic world, was also the main location where the oldest Mesopotamian, Greek and Egyptian astrological techniques were synthesized together in order to create horoscopic astrology. According to Firmicus Maternus, Dorotheus was originally a native of the city of Sidon (Firmicus, Mathesis, 2, 29: 2).