Marsilac is one of 96 districts of São Paulo, Brazil, located in the extreme south tip of the city in the subprefecture of Parelheiros.

[1] Its name is a tribute to engineer Jose Alfredo Marsilac, who developed many techniques for building roads and tunnels, even after losing 99% of his vision from being hit by a bomb in the Revolution of 1932.

Early settlement of the area owed mainly to the construction of the Mairinque–Santos by Estrada de Ferro Sorocabana connecting Mairinque and Santos, completed in 1935.

This is the most remote district of the capital, located about 60–70 kilometers from Marco Zero and only about 10–15 km from the Atlantic Ocean, which is visible from some points.

It is the poorest district and has the lowest Human Development Index (HDI) of the city of São Paulo.