The Hill House in Helensburgh, Scotland, was created by architects and designers Charles and Margaret Macdonald Mackintosh. The house is an example of the Modern Style (British Art Nouveau style). It was designed and built for the publisher Walter Blackie in 1902–1904. Mackintosh also designed the house interior, including furniture and fittings. In 1982, the house was donated to the National Trust for Scotland (NTS), which maintains and opens the house to visitors.

Helensburgh, located west of Glasgow, saw settlement by wealthy business people from the industrialised city. In 1902, Walter Blackie, a publisher from Blackie and Son, purchased a plot of land to build his new home. Talwin Morris suggested Charles Rennie Mackintosh as the architect for Hill House, and Blackie, despite Mackintosh's youthfulness, was convinced after seeing other houses designed by him. Blackie had specific requirements for the construction, seeking grey rough-cast walls and a slate roof instead of traditional materials like bricks and wood beams with red-tiled roofs commonly used in the west of Scotland. He also emphasized architectural effects through the massing of the parts rather than ornamentation, granting Mackintosh creative freedom in his design ideas.

Mackintosh carefully observed the everyday life of the Blackie family before creating any drawings, aiming to tailor the house to the needs of its occupants by addressing functional aspects before developing the design. There have been reports of the house being haunted by the ghost of Walter Blackie, with sightings of a tall, slender figure dressed in black with a long black cape, which vanished after entering the bedroom. Witnesses have also reported smelling cigar smoke in the house without any discernible source.