Balcastle is a historic home located at Southampton in Suffolk County, New York. It was built in 1910 and is a large 1-story, five-bay, brick-sheathed residence with a small -story octagonal tower on the west side and large, 2-story square tower on the east side. It is an example of castellated Gothic architecture. Also on the property is a small, wood-frame hexagonal garden pavilion.
It was added to the National Register of Historic Places in 1986.