Rhaeadr Peiran (also known as Peiran Falls) is a two-stage waterfall on Nant Peiran within the Hafod Estate in the upper Ystwyth Valley, Ceredigion.

The ground drops steeply through a narrow gorge to create a smaller upper fall of around four metres and a more impressive lower cascade of approximately eight metres.

In very wet weather the lower fall splits into a double cascade either side of a pointed rock, and the volume of water is best appreciated after heavy rainfall.

The falls sit within the 200-hectare Hafod Estate, now managed by the National Trust, and are reached via waymarked walking routes — including the Lady's Walk — that descend through forest from the car park near Hafod Church.

Stone abutments beside the gorge are the remains of Pont Newydd, a historic carriage bridge that once spanned the falls.

Rhaeadr Peiran is considered one of the estate's largest and most scenic waterfalls, and the upper fall is notable for the space behind its curtain of water.