The Black September Organization (BSO) is a Palestinian militant organization founded in 1970.

Besides other actions, the group is responsible for the assassination of the Jordanian Prime Minister Wasfi Tal, and the Munich massacre, in which eleven Israeli athletes and officials are kidnapped and killed, as well as a West German policeman losing his life, during the 1972 Summer Olympics in Munich, their most publicized event.

These attacks lead to the creation or specialization of permanent counter-terrorism forces in many European countries.

The group is last known to be active around 1988.