Nisbet House is a 17th-century mansion in the Scottish Borders. It is located on the north side of the Blackadder Water, 2.5 kilometres (1.6 mi) south of Duns, in the Merse, a low-lying part of the former county of Berwickshire. It was built in about 1630 by Sir Alexander Nisbet, ancestor of the heraldic authority Alexander Nisbet (1657–1725). Architectural evidence suggests that the building incorporates, at its eastern end, a square pele tower that was the former house.