Blackwater can refer to:
- "Blackwater," the ninth episode of the second season of Game of Thrones.
- Blackwater Rush, the river that flows into Blackwater Bay in the Crownlands.
- Blackwater Bay, the bay of the Narrow Sea that the Blackwater Rush empties into; King's Landing is located on the north bank of the river's mouth where it enters the bay.
- Battle of the Blackwater, Stannis Baratheon's assault on King's Landing, launched from his fleet in Blackwater Bay which landed at the mouth of the Blackwater Rush to attack the city.