Santos-o-Velho (Portuguese pronunciation: [ˈsɐ̃tuʃ u ˈveʎu]) is one of the 53 freguesias (civil parishes) of Lisbon, Portugal, with an area of 0.51 km² and 4,013 inhabitants (2001). It has a population density of 7899.6 inhabitants/km².

It is one of the best preserved historical parts of Lisbon, including Madragoa (former village in the outskirts of Central Lisbon), the Museum of Ancient Art, and many former convents and palaces (in which the current Embassy of France in included).

It is also known for its lively nightlife.