Sydenham House (anciently Sidelham, Sidraham, etc.) in the parish of Marystow in Devon, England, is a seventeenth-century manor house. The Grade I listed building is situated about thirteen miles south-west of Okehampton, on a 1,200 acres (490 ha) estate. It was built by Sir Thomas Wise (d.1629) between 1600 and 1612, incorporating an older structure. It was partially destroyed by fire in 2012. The gardens are Grade II listed in the National Register of Historic Parks and Gardens.