The Marshall Smith House is a historic house at 26 Liberty Street in Waltham, Massachusetts. The 2+1⁄2-story wood-frame house was built c. 1846–47; it is one of the city's few side-gable Greek Revival houses, with a single-story Doric porch spanning the main facade, a full entablature, and pedimented gable ends. The porch balustrade is a later addition, as are the western ell and northern window bay. Marshall Smith, the first owner, was a chair and harness maker.