Greywater Watch is a castle in the Neck. It is ruled by House Reed, a vassal house holding fealty to House Stark of Winterfell. It is the home of Jojen and Meera Reed and their father, Lord Howland Reed.
In the books
In A Song of Ice and Fire books, Greywater Watch is the seat of House Reed, one of the most loyal vassals of the Starks. No raven can reach Greywater Watch because it is said to be constantly moving.
Greywater Watch has not been mentioned in the series yet except for a map that mistakenly refers to the settlement as 'Greytower Watch.'
See also
Template:The North