The Stoa of Attalos (also spelled Attalus) was a stoa (covered walkway or portico) in the Agora of Athens, Greece. It was built by and named after King Attalos II of Pergamon, who ruled between 159 BC and 138 BC. The current building was reconstructed in 1952–1956 by the American School of Classical Studies at Athens and currently houses the Museum of the Ancient Agora.

The Stoa of Attalos houses the Museum of the Ancient Agora. Its exhibits are mostly connected with the Athenian democracy. The collection of the museum includes clay, bronze and glass objects, sculptures, coins and inscriptions from the 7th to the 5th century BC, as well as pottery of the Byzantine period and the Turkish conquest.