Thrasybulus (died 388 bc) was an Athenian general and democratic leader.
Thrasybulus’ public career began in 411 bc, when he frustrated the oligarchic rising in Samos. Elected general by the troops, he effected the recall of Alcibiades, a former general accused of having profaned the hermae (small sacred statues) of Athens, and assisted him in several successful naval campaigns. In 404, when exiled by the Thirty (the oligarchy at Athens), he retired to Thebes. In the following winter, with 70 men, he seized Phyle, a hill fort on Mt. Parnes near Athens. His supporters soon increased, and with 1,000 men he repelled an attack by the oligarchs. In autumn 403, following skirmishes with a Spartan expedition under King Pausanias, a reconciliation was effected and democracy was restored. Thrasybulus was now the hero of the people; but a decree by which he secured the franchise for all his noncitizen followers was rescinded as illegal.
In 395 Thrasybulus induced Athens to join the Theban League against Sparta. He effected a democratic revolution at Byzantium and renewed the toll on the Bosporus trade. After a successful attack on Lesbos in 389/8, he sailed south and was killed at Aspendus, where his financial exactions had made him unpopular.