John O'Gaunt's Castle was a royal hunting lodge in the West Riding of Yorkshire in England.

The castle was considered to be the hunting lodge of John O'Gaunt, Duke of Lancaster, who was Lord of the Manor of Knaresborough for twenty-eight years until 1399.

[citation needed] Strongly sited on the end of a spur at Haverah Park, is a ditched platform 35mx30m which had a curtain wall and a gatehouse, with a bridge over the moat.

Within are buried footings of a central tower, 15m square, and 1 wall which probably formed part of a range.

[1] The hunting lodge was a stone tower built atop on a square foundation.