Apollonius (or Apollonios, Greek: Ἀπολλώνιος; 3rd century BC) was the dioiketes or chief finance minister of Egypt during the reign of Ptolemy II Philadelphus (r. 283–246 B.C.). Little is known about his personal life; in ancient documents, he is called simply "Apollonius the dioiketes" without recording his home city or his father's name. But a great amount of information has survived about his public role, in the archive of papyri kept by his assistant Zenon.
Apollonius was dioiketes from about 262 to 245 B.C. As well as his official role, he was an important merchant and land-owner. He owned estates both abroad in Galilee and in Philadelphia in Egypt. In 252 B.C. he accompanied Berenice, the daughter of Ptolemy, as far as Sidon before her marriage to the Seleucid king Antiochus II. Although the extent of his influence over the king's policies has been disputed,  it was during his term of office that the economic and administrative system of the Ptolemaic Kingdom was fully developed, which made the kingdom by far the most prosperous of the Hellenistic states.
As dioiketes he was succeeded by Sosibius.
- OGIS 53 (Greek inscription) - English translation.
- Günther Hölbl, History of the Ptolemaic Empire (Routledge, 2001), pp. 58-59.
- Günther Hölbl, History of the Ptolemaic Empire (Routledge, 2001), p. 44.
- Cambridge Ancient History, vol. 7.1, pp. 143-4.
- Günther Hölbl, History of the Ptolemaic Empire (Routledge, 2001), p. 63.
- Dorothy J. Thompson, Economic Reforms in the Mid-Reign of Ptolemy Philadelphus, in P.McKechnie & Ph.Guillaume, Ptolemy II Philadelphus and His World, (Leiden: Brill, 2008) ISBN 978-90-04-17089-6
- Michael Rostovtzeff, A large estate in Egypt in the third century B.C.: a study in economic history, (Madison, 1922) - at archive.org
- Introduction to the Zenon Papyri by University of Michigan