Wynnstay is a country house within an important landscaped park 1.3 km (0.75 miles) south-east of Ruabon, near Wrexham, Wales.

Wynnstay was Brown's largest commission in Wales, work beginning in 1774 and completed in 1784, a year after his death.

He replaced the older formal gardens with lawns which swept right up to the house overlooking the lake.

After the house was vacated by the Williams-Wynn family in the mid-20th century, in favour of the nearby Plas Belan on the Wynnstay estate, it was bought by Lindisfarne College.

When the school closed due to bankruptcy, the building was converted to flats and several private houses.