Aristion (died 86 BC in Athens) was a philosopher and tyrant of Athens from 88 BC to 86 BC. Aristion joined forces with Mithridates against the Romans under Lucius Cornelius Sulla in the First Mithridatic war, but to no avail. On March 1, 86 BC, Athens was conquered by Sulla and Aristion was executed. He is called Athenion by Posidonius, and he may be the same person, or he may be a second tyrant whose story became confused with the first.

His early history is preserved by Athenaeus, on the authority of Posidonius. Posidonius calls him Athenion and makes him a Peripatetic philosopher, whereas others, Pausanias, Appian, and Plutarch, call him Aristion, and Appian calls him an Epicurean philosopher. There is no universally accepted resolution to this confusion, and it is possible that there were two separate tyrants who held power in Athens in quick succession during the First Mithridatic War whose stories became conflated together.

Athenion (or Aristion) was the illegitimate son of a Peripatetic philosopher, also called Athenion, to whose party he succeeded, and so became an Athenian citizen. He married early, and began at the same time to teach philosophy, which he did with great success at Messene and Larissa, On returning to Athens with a considerable fortune, he was named ambassador to Mithridates, king of Pontus, then at war with Rome, and became one of his most intimate friends and counsellors. His letters to Athens represented the power of Mithridates in such glowing colours, that his countrymen began to conceive of hopes of throwing off Roman rule. Mithridates then sent him to Athens (c. 88 BC), where he soon contrived, through the king's patronage, to assume the tyranny. His government seems to have been of the most cruel character, so that he is spoken of with horror by Plutarch, and classed by him with Nabis and Catiline. He sent Apellicon of Teos to plunder the sacred treasury of Delos, though Appian says that this had already been done for him by Mithridates, and adds that it was by means of the money resulting from this robbery that Aristion was enabled to obtain supreme power. Meanwhile, Sulla landed in Greece, and immediately laid siege to Athens and Piraeus, the latter of which was occupied by Archelaus, the general of Mithridates. The sufferings within the city from famine were so dreadful that cannibalism was reported. Eventually Athens was stormed, and Sulla gave orders to spare neither age nor sex. Aristion fled to the Acropolis, having first burned the Odeon, in case Sulla should use the woodwork for battering rams and other instruments of attack. The Acropolis, however, was soon taken, and Aristion dragged to execution from the altar of Athena and poisoned. Pausanias attributes the unpleasant disease that later killed Sulla as divine vengeance for this impiety.