Llanbrynmair or Llanbryn-mair[2] (Welsh pronunciationⓘ) is a village, community and electoral ward in Montgomeryshire, Powys, Wales on the A470 road between Caersws and Machynlleth.

The current centre (formerly called "Wynnstay") at the junction of the A470 and B4518 rose to local prominence with the building of the new turnpike road in 1821 and the arrival of the railway line between Newtown and Machynlleth in 1861.

The Cambrian railway line, built in the 1860s, runs through Llanbrynmair and for a time provided an outlet for the mines at Dylife, 8 miles (13 km) south.

[6] Much of the area was part of the large Wynnstay Estate owned for generations by the families of Sir Watcyn Williams Wynne.

A large proportion of these emigrants settled in western Ohio, particularly in the rural farming communities of Paddy's Run (now Shandon), Gomer and Venedocia.