The first notable Alcmaeonid was Megacles, who was the Archon Eponymous of Athens in the 7th century BC. He was responsible for killing the followers of Cylon of Athens during the attempted coup of 632 BC, as Cylon had taken refuge as a suppliant at the temple of Athena. As a result of their actions, Megacles and his Alcmaeonid followers were the subject of an ongoing curse and were exiled from the city. Even the bodies of buried Alcmaeonidae were dug up and removed from the city limits.
The Alcmaeonids were allowed back into the city in 594 BC, during the archonship of Solon. During the tyranny of Pisistratus, the Alcmaeonid Megacles married his daughter to Pisistratus, but when the tyrant refused to have children with her, Megacles banished him. Later the Alcmaeonids would claim to have been exiled following Pisistratus' return in 546 BC so as to distance themselves from possible accusations of complicity, but epigraphic evidence in fact proves that Cleisthenes was archon for the year 525-24. Megacles was able to marry (for a second or third time) Agarista, the daughter of the tyrant Cleisthenes of Sicyon. They had two sons, Hippocrates and Cleisthenes, the reformer of the Athenian democracy. Hippocrates' daughter was Agariste, the mother of Pericles.
This Cleisthenes overthrew Hippias, the son and successor of Pisistratus, in 508 BC. He had bribed the oracle at Delphi (which the Alcmaeonidae had helped to build while they were in exile) to convince the Spartans to help him, which they reluctantly did. Cleisthenes was, at first, opposed by some who felt the curse made the Alcmaeonidae ineligible to rule; the Spartan king Cleomenes I even turned against Cleisthenes and the latter was briefly exiled once more. However, the citizens called for Cleisthenes to return, and the restored Alcmaeonids were responsible for laying the foundations of Athenian democracy.
The Alcmaeonidae were said to have negotiated for an alliance with the Persians during the Persian Wars, despite the fact that Athens was leading the resistance to the Persian invasion. Pericles and Alcibiades also belonged to the Alcmaeonidae, and during the Peloponnesian War the Spartans referred to the family's curse in an attempt to discredit Pericles. Alcibiades, as the previous generation of Alcmaeonidae had done, tried to ally with the Persians after he was accused of impiety. The family disappeared after Athens's defeat in the Peloponnesian War.
Because of a family tradition of naming descendants after their forebears, members of the family can easily be confused. Hence, what follows is a partial family tree of the historical Alcmaeonid family. Males are in blue, females in red, and those related by marriage in white.
|Megacles (6th perpetual archon)|
|Alcmaeon (last perpetual archon) (died 753 BC)|
|Megacles (7th century BC)|
|Alcmaeon||Cleisthenes of Sicyon|
|Megacles||Agariste of Sicyon|
Victor, Pythian Games
(ostracized 486 BC)