Ptolemy Alorites (or Ptolemy of Aloros) was a Macedonian who attempted to seize the throne from Alexander II, then acted a regent for Alexander's brother Perdiccas III before being assassinated by Perdiccas, who seized power in his own name. Ptolemy's activities were probably the reason that the young Philip II spent some time in exile in Thebes, where he is said to have received an excellent military education.
Ptolemy may have been married to Eurynoe, the daughter of King Amyntas III of Macedon, and was possibly involved in a plot to overthrown Amyntas, alongside Amyntas's wife Eurydice. However this connection is unclear, as it comes from one possible reading of a passage in Justin that only gives the plotter as Eurydice's son-in-law. Diodorus refers to Ptolemy as the brother-in-law of Alexander and his brother Perdiccas, but doesn't give the name of Ptolemy's wife.
Ptolemy first came to prominence after the death of Amyntas II (probably of natural causes, after a reign of 24 years, an impressive achievement in Macedon at this period). After Amyntas's death he was succeeded by his eldest son Alexander II.
Our two main sources for the activities of Ptolemy are Diodorus and Plutach's life of the great Theban leader Pelopidas. Diodorus gives a few mentions. Pelopidas first appears in Macedon during Alexander's reign, heading north after visiting Thessaly to overthrow Alexander of Pherae. He formed an alliance with Alexander, and took his brother Philip hostage back to Thebes. Soon afterwards Alexander was assassinated by Ptolemy, who ruled as king of Macedon for three years, before being assassinated in turn by Alexander's younger brother Perdiccas.
Plutarch gives more details. Once again Pelopidas was in Thessaly to deal with Alexander of Pherae, but he was then drawn north to deal with a civil war in Macedon, being fought between Ptolemy and Alexander II. Pelopidas had been invited in by both sides, settled their differences, and as in Diodorus took Philip as one of his hostages. Alexander continued as king.
Pelopidas's second intervention in Thessaly didn't go as well. This time he was sent as an ambassador, without troops, and when Alexander of Pherae turned out to be more troublesome than expected, he had to raise an army in Thessaly. This came just after Ptolemy had killed Alexander II of Macedon, and was ruling the kingdom. Plutarch doesn't call Ptolemy king. Pelopidas raised a force of mercenaries and advanced into Macedon. Ptolemy managed to bribe the mercenaries, but he was still unwilling to risk a clash with Thebes, and so agreed to act as regent for Alexander II's brother Perdiccas III. On his way back from Macedon, Pelopidas was captured by Alexander of Pherae, and had to be rescued by an army sent from Thebes.
Aeschines, in his Speech on the Embassy, records an incident where the Athenian general Iphicrates intervened in Macedon to support Perdiccas and overthrow a rival claimant to the throne, Pausanias. Ptolemy is recorded here as having been made regent, but then acting ungratefully by supporting Amphipolis in its struggles against Athens.
Ptolemy remained in power in Macedon for three years, before in 364 BC he was assassinated by Perdiccas III, who them ruled in his own right, before being killed in battle against the Illyrians, probably in 360 BC.