Onllwyn is a village in Neath Port Talbot, Wales.
It is situated within the SA10 postcode district, which is within the Neath post town.
The full list of postcode districts within the Neath post town is as follows:
The Neath post town is within the Swansea postcode area.
Administrative Ward: Onllwyn
Administrative District: Neath Port Talbot
Country: Wales
UK Parliament: Neath