Baydon is a village and civil parish in Wiltshire, England about south-east of Swindon. The eastern boundary of the parish forms part of the county boundary with Berkshire and the village is about north-west of the West Berkshire market town of Hungerford.
The Church of England parish church of Saint Nicholas has a Norman nave and two-bay north arcade. The south aisle and northern clerestory are Early English Gothic. The north aisle was rebuilt in 1857-58 by the Gothic Revival architect G.E. Street. The south clerestory is Perpendicular Gothic.
Sir Isaac Newton bought an estate in Baydon which he settled on three of his grand-nephews and nieces days before his death in 1727. He later admitted that he had overpaid for it.
The M4 motorway which passes just north of the village was opened on 22 December 1971.